{
  "spec_version": "3",
  "endpoint": "timeline",
  "stock_code": "5715",
  "company_name": "古河機械金属",
  "content_lang": "ja",
  "meta_lang": "en",
  "canonical_url": "https://the-shashi.com/tse/5715/",
  "api_url": "/api/5715/timeline.json",
  "updated": "2026-08-21",
  "license": "© 2026 Yutaka Sugiura. All rights reserved.",
  "attribution": "The社史 (the-shashi.com) — https://the-shashi.com/tse/5715/",
  "source": {
    "primary": [
      "有価証券報告書",
      "公式サイト沿革"
    ],
    "extraction": "有価証券報告書の沿革を基礎に、社史・報道で補完",
    "row_field": "source"
  },
  "timeline": [
    {
      "date": "1875/8",
      "importance": 2,
      "event": "古河市兵衛が草倉銅山（新潟県）の経営を開始し創業",
      "source": "有価証券報告書"
    },
    {
      "date": "1877/2",
      "importance": 3,
      "event": "足尾銅山（栃木県）を譲り受け経営を開始",
      "source": "有価証券報告書"
    },
    {
      "date": "1894/9",
      "importance": 1,
      "event": "下山田炭鉱（福岡県）を譲り受け石炭事業へ参入",
      "source": "有価証券報告書"
    },
    {
      "date": "1900",
      "importance": 1,
      "event": "足尾銅山に機械工場を設置し機械部門へ参入",
      "source": "公式サイト沿革"
    },
    {
      "date": "1905/3",
      "importance": 2,
      "event": "個人経営から会社組織に変更し古河鉱業会社を設立",
      "source": "有価証券報告書"
    },
    {
      "date": "1911/11",
      "importance": 1,
      "event": "組織変更により古河合名会社を設立",
      "source": "有価証券報告書"
    },
    {
      "date": "1914",
      "importance": 1,
      "event": "日本初のさく岩機を製作",
      "source": "公式サイト沿革"
    },
    {
      "date": "1918/4",
      "importance": 2,
      "event": "古河合名会社の鉱業部門を独立させ古河鉱業を設立",
      "source": "有価証券報告書"
    },
    {
      "date": "1920/4",
      "importance": 2,
      "event": "日光電気精銅所を現物出資し古河電気工業を設立",
      "source": "公式サイト沿革"
    },
    {
      "date": "1933/3",
      "importance": 1,
      "event": "金属部門を古河合名会社へ移管し商号を古河石炭鉱業に変更",
      "source": "有価証券報告書"
    },
    {
      "date": "1941/2",
      "importance": 2,
      "event": "古河合名会社と合併し商号を古河鉱業に変更",
      "source": "有価証券報告書"
    },
    {
      "date": "1942/4",
      "importance": 1,
      "event": "足尾の機械工場を足尾製作所として足尾鉱業所から独立",
      "source": "有価証券報告書"
    },
    {
      "date": "1942/9",
      "importance": 1,
      "event": "増資により株式の一部を公開",
      "source": "有価証券報告書"
    },
    {
      "date": "1944/8",
      "importance": 1,
      "event": "東亜化学製煉大阪製煉工場を買収し化学部門へ参入",
      "source": "有価証券報告書"
    },
    {
      "date": "1949/5",
      "importance": 1,
      "event": "東京証券取引所第一部に上場",
      "source": "有価証券報告書"
    },
    {
      "date": "1950/2",
      "importance": 1,
      "event": "群馬県高崎市にさく岩機部門の高崎工場を建設",
      "source": "有価証券報告書"
    },
    {
      "date": "1956",
      "importance": 2,
      "event": "足尾製錬所に日本初の自熔製錬設備が完成",
      "source": "公式サイト沿革"
    },
    {
      "date": "1962",
      "importance": 1,
      "event": "小山工場でクローラショベルの生産を開始",
      "source": "公式サイト沿革"
    },
    {
      "date": "1970/1",
      "importance": 2,
      "event": "下山田炭鉱を閉山し石炭採掘事業から撤退",
      "source": "有価証券報告書"
    },
    {
      "date": "1972/6",
      "importance": 1,
      "event": "福島県いわき市にいわき工場、東京都日野市に日野研究所を建設",
      "source": "有価証券報告書"
    },
    {
      "date": "1973/2",
      "importance": 3,
      "event": "足尾銅山を閉山",
      "source": "有価証券報告書"
    },
    {
      "date": "1973/4",
      "importance": 1,
      "event": "栃木県壬生町に建設機械部門の壬生工場を建設",
      "source": "有価証券報告書"
    },
    {
      "date": "1987/3",
      "importance": 2,
      "event": "トラッククレーン製造のユニックを買収",
      "source": "有価証券報告書"
    },
    {
      "date": "1989/10",
      "importance": 3,
      "event": "商号を古河鉱業から古河機械金属に変更",
      "source": "有価証券報告書"
    },
    {
      "date": "1990/9",
      "importance": 1,
      "event": "油圧ブレーカ製造の Gougler Industries（米国）を買収",
      "source": "有価証券報告書"
    },
    {
      "date": "1997/1",
      "importance": 1,
      "event": "銅製錬会社 Port Kembla Copper（オーストラリア）を設立",
      "source": "有価証券報告書"
    },
    {
      "date": "1999/4",
      "importance": 2,
      "event": "建機部門を分離し生産を古河建機、販売を古河建機販売へ移管",
      "source": "有価証券報告書"
    },
    {
      "date": "2000/4",
      "importance": 2,
      "event": "古河建機を日立建機との合弁会社化し日立古河建機に商号変更",
      "source": "有価証券報告書"
    },
    {
      "date": "2003/9",
      "importance": 1,
      "event": "日光発電事務所の水力発電事業を会社分割し事業譲渡",
      "source": "有価証券報告書"
    },
    {
      "date": "2003/10",
      "importance": 1,
      "event": "鋳造品事業を古河キャステックへ営業譲渡",
      "source": "有価証券報告書"
    },
    {
      "date": "2004/3",
      "importance": 1,
      "event": "金属製錬事業を会社分割し古河メタルリソースを新設",
      "source": "有価証券報告書"
    },
    {
      "date": "2004/10",
      "importance": 3,
      "event": "日立古河建機の株式を日立建機へ譲渡し建設機械事業から撤退",
      "source": "有価証券報告書"
    },
    {
      "date": "2005/3",
      "importance": 3,
      "event": "主要6事業部門を会社分割し事業持株会社体制へ移行",
      "source": "有価証券報告書"
    },
    {
      "date": "2008/7",
      "importance": 1,
      "event": "燃料事業を会社分割し古河コマースへ承継",
      "source": "有価証券報告書"
    },
    {
      "date": "2009/12",
      "importance": 1,
      "event": "塗料・化成品製造のトウペを連結子会社化",
      "source": "有価証券報告書"
    },
    {
      "date": "2012/10",
      "importance": 1,
      "event": "古河コマースの株式を宇佐美鉱油へ譲渡し燃料事業から撤退",
      "source": "有価証券報告書"
    },
    {
      "date": "2013/3",
      "importance": 2,
      "event": "トウペの株式を日本ゼオンへ譲渡し塗料事業から撤退",
      "source": "有価証券報告書"
    },
    {
      "date": "2021/10",
      "importance": 1,
      "event": "金属粉体製造の山石金属を買収",
      "source": "有価証券報告書"
    },
    {
      "date": "2022/4",
      "importance": 1,
      "event": "東京証券取引所の市場区分見直しによりプライム市場へ移行",
      "source": "有価証券報告書"
    }
  ]
}