MM Bridge Co., Ltd.
Japanese bridge and steel-structure engineering company with roots in Mitsubishi Heavy Industries, specializing in design, fabrication, erection and maintenance of major bridges.
Last updated September 29, 2026
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Overview
MM Bridge Co., Ltd. (エム・エム ブリッジ株式会社) is a Japanese engineering company focused on the design, fabrication, erection and maintenance of bridges and steel structures. Its lineage reaches back to the Mitsubishi Heavy Industries bridge division, which itself traces its origins to the government-run Nagasaki Iron Works established in 1868 and the building of the Kurogane Bridge in Nagasaki Prefecture, described by the company as Japan's first iron bridge. Over more than 155 years the bridge business accumulated a portfolio of landmark structures, including the Akashi Kaikyo Bridge, the Seto Ohashi bridges, the Yokohama Bay Bridge, the Tatara Bridge and the Kurushima Kaikyo bridges. The modern company was incorporated in 2015 as MM Bridge Co., Ltd., when the bridge operations were reorganized under a joint ownership structure: Miyaji Engineering Group, Inc. holds 51% and Mitsubishi Heavy Industries, Ltd. holds 49%. The company is headquartered in Nishi-ku, Hiroshima, Japan, and operates through a network of offices, branches and plants, including the Ichihara Plant, Toyama Office, Nagasaki Office, West Japan Branch and Hiroshima Equipment Center. MM Bridge positions itself as a bridge specialist capable of integrated delivery from design through fabrication to on-site erection, with particular strength in long-span and large-scale bridges, special erection methods, and maintenance, renewal and seismic/vibration control technologies such as damper braces and damping devices. Its project stories include the Tate-Kohoku and Kesennuma Bay Crossing Bridge works, the restoration of the Daiichi Shirakawa Railway Bridge damaged by the Kumamoto earthquake, the Ariake-Chikugo River Bridge, and the longevity measures for the Dojima Bridge in Osaka. The company also pursues sustainability-related technology, including the GMC coral growth substrate developed from the observation of coral naturally growing on a floating pier it constructed. It has received industry recognition, including the 7th Nikkenren Civil Engineering Award for the Kire-Uriwari Bridge large-scale renewal project and the 2025 JSCE Kansai Branch Technical Award for the Aioi Bridge superstructure widening work. MM Bridge communicates under the slogan "BRIDGE PEOPLE, BRIDGE DREAMS."
History
The roots of MM Bridge lie in the bridge business of Mitsubishi Heavy Industries, which the company traces back to the government-run Nagasaki Iron Works established in 1868 (Keio 4), the predecessor of Mitsubishi Heavy Industries. The Kurogane Bridge in Nagasaki Prefecture, described as Japan's first iron bridge, is presented as the origin of the company's engineering lineage. Mitsubishi Heavy Industries itself was founded in 1884. As the bridge division of Mitsubishi Heavy Industries, the business constructed many notable bridges in response to the needs of each era. In 1966 it completed the Maya Bridge in Hyogo Prefecture, described as Japan's first full-scale cable-stayed bridge. In 1968 it completed the Aki Bridge in Hiroshima Prefecture, Japan's first Nielsen bridge. In 1972 Mitsubishi Heavy Industries Engineering & Construction Co., Ltd. was established as a wholly owned subsidiary. In 1974 the Minato Bridge in Osaka Prefecture was completed, noted as Japan's largest truss bridge and using ultra-high-tensile steel HT80. In 1983 the Matadi Bridge was completed in the Republic of Zaire (now the Democratic Republic of the Congo). In 1988 the Second Bosphorus Bridge in Turkey and the Yokohama Bay Bridge in Kanagawa Prefecture were completed, the latter then Japan's largest cable-stayed bridge, along with the Seto Ohashi bridges between Okayama and Kagawa, the world's longest railway-road combined bridge. In 1992 the Rama IV Bridge in Thailand was completed. In 1998 the Akashi Kaikyo Bridge in Hyogo Prefecture, one of the world's largest suspension bridges, was completed. In 1999 the Ujina Bridge in Hiroshima Prefecture (Japan's largest plate girder bridge), the Tatara Bridge between Hiroshima and Ehime (Japan's largest cable-stayed bridge), and the Kurushima Kaikyo bridges in Ehime (the world's first triple suspension bridge) were completed. In 2004 the company began research on coral regeneration and growth promotion technology (GMC) after discovering coral naturally growing on a floating pier it had constructed. In 2005 the Megami Bridge in Nagasaki Prefecture, one of Japan's ten largest cable-stayed bridges, was completed. In 2006 Mitsubishi Heavy Industries Bridge Engineering Co., Ltd. was established as a wholly owned subsidiary of Mitsubishi Heavy Industries, succeeding Mitsubishi Heavy Industries Engineering & Construction Co., Ltd. and absorbing the bridge and coastal structure businesses of Mitsubishi Heavy Industries through a company split. In 2007 it absorbed the chimney business of Mitsubishi Heavy Industries. In 2008 it changed its name to Mitsubishi Heavy Industries Steel Structure Engineering Co., Ltd., a wholly owned subsidiary of Mitsubishi Heavy Industries, absorbing the gas holder and beer tank businesses of Mitsubishi Heavy Industries and receiving a technology license for the seismic isolation and vibration damping business. In 2009 the Chiba Plant was established. In 2011 the Hiroshima Airport Bridge in Hiroshima Prefecture, Japan's largest arch bridge, was completed; two TMD damping devices were delivered for Tokyo Skytree; the Shinminato Bridge in Toyama Prefecture, one of Japan's ten largest cable-stayed bridges, was completed; and the Tokyo Gate Bridge in Tokyo, one of Japan's largest truss bridges, was completed. In 2015 the company changed its name to MM Bridge Co., Ltd., becoming a subsidiary owned 51% by Miyaji Engineering Group, Inc. and 49% by Mitsubishi Heavy Industries, Ltd. That year it also carried out longevity measures for the Eitai Bridge in Tokyo, an arch bridge designated a national important cultural property, and closed the Chiba Plant. In 2016 the Ichihara Plant was established. In 2017 the Toyama Office opened. In 2018 the Nagasaki Office opened. In 2020 the Kansai Sales Office was renamed the West Japan Branch; longevity measures were carried out for the Dojima Bridge in Osaka Prefecture, an arch bridge of high historical and cultural value; the Hiroshima Equipment Center opened; the floating pier and other facilities for the local Itsukushima Port in Hiroshima Prefecture (Miyajimaguchi area) were fabricated and installed; and the Takase Bridge in Niigata Prefecture saw the company's first deck slab replacement work on an expressway in service. In 2021 the Nasu Equipment Center was transferred from Mitsubishi Heavy Industries Machinery Systems, Ltd.; the Kesennuma Bay Crossing Bridge (nicknamed Kanae Ohashi) in Miyagi Prefecture, one of Japan's leading cable-stayed bridges and a symbol of reconstruction after the Great East Japan Earthquake, was completed; and the Ariake-Chikugo River Bridge in Fukuoka Prefecture, Japan's first steel four-span continuous (two-unit) single-plane half-through arch bridge, was completed. In 2022 the Daiichi Shirakawa Railway Bridge replacement in Kumamoto Prefecture contributed to the full reopening of the Minamiaso Railway, which had been damaged by the Kumamoto earthquake.
- 2021
Nasu Equipment Center transferred; Kesennuma Bay Crossing Bridge and Ariake-Chikugo River Bridge completed
- 2020
Kansai Sales Office renamed West Japan Branch; Dojima Bridge longevity measures; Hiroshima Equipment Center opened; Takase Bridge deck replacement
- 2018
Nagasaki Office opened
- 2017
Toyama Office opened
- 2016
Ichihara Plant established
- 2015
Renamed MM Bridge Co., Ltd.; Miyaji Engineering Group 51% and Mitsubishi Heavy Industries 49%; Eitai Bridge longevity measures; Chiba Plant closed
- 2011
Hiroshima Airport Bridge, Shinminato Bridge and Tokyo Gate Bridge completed; TMD devices delivered for Tokyo Skytree
- 2009
Chiba Plant established
- 2008
Renamed Mitsubishi Heavy Industries Steel Structure Engineering Co., Ltd.
- 2007
Absorbed Mitsubishi Heavy Industries' chimney business
Products and positioning
Bridge specialist with integrated design-to-erection capability, strong in long-span and large-scale bridges, special construction methods and maintenance/renewal technologies.
Bridge design and engineering
Steel bridge fabrication
Bridge erection and construction
Maintenance, renewal and seismic retrofit
Damper braces and vibration control devices
Steel structures and coastal structures
GMC coral growth substrate
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