Company history

The company begins in a policy, not a hunch. As the Meiji government sold its state-run mines into private hands, Mitsubishi Shokai bought the Yoshioka mine in Okayama in 1873 and entered metal mining; Osarizawa followed in 1887, Ikuno and Akenobe in 1896. Coal came with it — Oyubari, Takashima, Hashima — and by the early twentieth century Mitsubishi held one of the largest non-ferrous mining networks in Japan. In 1918 the mining division was spun out as Mitsubishi Mining, a core company of the zaibatsu whose metals and coal fed the state as much as the market.

War pulled it downstream. To meet military and heavy-industry demand, Mitsubishi Mining built metal-processing plants in quick succession — Tokyo Metal Industry in February 1942 (today the Oi works), Niigata Metal Industry in January 1944, a non-ferrous works in April 1945 (today Okegawa). These fabrication sites, not the mines, would become the operating base of the postwar company.

Then the zaibatsu was taken apart. Mitsubishi Mining was designated under the Deconcentration Law in February 1948, and in 1950 the company was split along its two materials: coal stayed with Mitsubishi Mining, while the non-ferrous business — mines, smelters and fabrication together — was cut loose as a successor firm. It was a separation that would take forty years to reverse.

The non-ferrous successor started in 1950 as Taihei Mining, capitalised at $1.9M (¥700m) and carrying the whole of the mining, smelting and fabrication assets. It was renamed Mitsubishi Metal Mining in December 1952 and later simply Mitsubishi Metal, running on prewar technique and prewar mining know-how. Its four principal mines — Osarizawa, Hosokura, Ikuno, Akenobe — each employed thousands of people and each anchored a company town. That was the strength of the business, and the thing that would make shrinking it so slow.

Through the 1950s and 1960s the company thickened all three pillars: the Akita smelter in December 1953, the Myoho mine bought in October 1954, Mitsubishi Reynolds Aluminium with the American Reynolds Metals in January 1962, Onahama Smelting in December 1963. It also stepped outside non-ferrous metals for the first time, tying up with Germany's Walter to form Mitsubishi Walter Tools and entering cemented-carbide cutting tools — at the time a minor complement to a business still built on mines.

By the year to March 1968, with the loss-making mining division pared back and the Okegawa plant out of the red, sales reached $133M (¥48bn) and after-tax profit $2.3M (¥830m), enough to sustain a 10% dividend. The carbide-tool investment looked marginal then. It was in fact the hedge that would carry the company once the mines went.

The 1971 Nixon shock pushed the yen up while ore grades fell, and Japanese mines stopped paying. Mitsubishi Metal began closing them in 1972 — first hiving off Shimokawa, Furutobe, Matsuki, Hosokura and Akenobe as subsidiaries, then shutting Ikuno in 1973 and Osarizawa in 1978. After the 1985 Plaza Accord drove the yen higher still, the last four mines closed across 1986 and 1987. The retreat had taken fifteen years.

The length was the policy. Closing all of them at once would have destroyed the local economies the mines supported, so the company built processing plants on the vacated sites and let the transition run slowly. What the organisation learned in the process — how to wind down an unprofitable business on a decade-long clock rather than a quarterly one — became a permanent habit of management.

It also, paradoxically, made a merger possible. Only once the mines and the collieries were finally settled did the two halves separated in 1950 fit back together. President Fujimura Masaya later observed that earlier generations of leaders had always wanted to reunite the companies but had never had the conditions for it. Contraction, not growth, supplied them: in February 1990 Mitsubishi Metal and Mitsubishi Mining & Cement merged.

The merger of February 1990 created Mitsubishi Materials and put the non-ferrous metals and cement of the old Mitsubishi Mining back under one roof after some forty years apart. Consolidated sales reached $9.2B (¥1.17tn) in the year to March 1992, on three main legs — smelting, cement and cemented-carbide tools — and the long-range plan “MAX21” set a ten-year target of ¥1.8 trillion. The direction was addition.

Some of it worked and some did not. Silicon wafers were merged with Sumitomo Metal Industries in 2002 to create what is now SUMCO, giving the company real weight in large-diameter wafers; a planned copper smelter in Texas was killed by local environmental opposition. Three consecutive years of net losses through the year to March 2004 showed how heavily commodity prices and portfolio weight bore on results.

Underneath, the group had grown to roughly 200 companies — smelting, cement, carbide tools, electronic materials, components, energy. Breadth cushioned the swings of any one market, but it also put more distance between the executive floor and the edges of the business than the executive floor could see across. In December 2017 that distance surfaced as falsified quality data at group subsidiaries; in 2019 a subsidiary, Universal Can, was fined $94.5M (¥10bn) for antitrust violations, and the year to March 2020 carried an extraordinary loss of $97.4M (¥10bn). The conclusion drawn inside the company was not that individual controls had failed but that the portfolio itself had to be cut back.

Ono Naoki became president in 2018 and published a three-year mid-term strategy in March 2020 that named four businesses to be shrunk — sintered parts, copper tube, cement and aluminium. The sintered-parts maker Diamet was sold in December 2020 against a restructuring loss of $196.7M (¥21bn); Universal Can went in 2022, ending the can business outright. Resources came back the other way into cemented-carbide tools, where the acquisition of Mitsubishi Hitachi Tool was settled in April 2020, adding end mills and die-machining tools to the range. Tungsten supply was managed the same way: the recycled-feedstock share of about 70% inherited with H.C. Starck became the lever for reducing dependence on China.

The largest reversal was cement. In April 2022 the business acquired in the 1990 merger was moved into UBE Mitsubishi Cement, a 50-50 venture with Ube Industries — the end of a separation that had run in stages since the 1998 sales tie-up, twenty-four years in all. Closing the Aomori plant and idling kilns cost Mitsubishi Materials an equity-method loss of $59.1M (¥8bn) in the year to March 2023. Giving up cement rewrote the company's own definition of itself.

Copper is now going the same way. Terms of trade for smelters — the treatment and refining charges paid when buying concentrate — deteriorated badly, and a company carrying that purchasing risk alone could not hold its margins. On 11 November 2025 Mitsubishi Materials agreed in principle with JX Metals, Mitsui Mining & Smelting and Marubeni to consolidate concentrate purchasing and electrolytic copper sales into Pan Pacific Copper; on the 26th, President Tanaka Tetsuya, appointed that April, set out a mid-term strategy built on resource circulation and the expansion of secondary-feedstock smelting. Thirty-five years after a merger meant to make it comprehensive, the company is deliberately becoming a specialist.