{
  "spec_version": "5",
  "endpoint": "ceo-person",
  "stock_code": "5404",
  "company_name": "日本鋼管",
  "content_lang": "ja",
  "meta_lang": "en",
  "canonical_url": "https://the-shashi.com/tse/5404/executives/ceo/shimogaichi-yoichi/",
  "api_url": "/api/5404/ceo/shimogaichi-yoichi.json",
  "updated": "2026-10-27",
  "license": "© 2026 Yutaka Sugiura. All rights reserved.",
  "attribution": "The社史 (the-shashi.com) — https://the-shashi.com/tse/5404/executives/ceo/shimogaichi-yoichi/",
  "source": {
    "person": {
      "primary": [
        "有価証券報告書（役員の状況）"
      ],
      "extraction": "EDINET の XBRL から機械抽出した役員表を土台に、雑誌記事・社史・報道で経歴と出自を補完",
      "caveat": "在任区間は career の is_ceo_appointed が正本。退任年月は次の代の就任年月から決まる"
    }
  },
  "person": {
    "slug": "shimogaichi-yoichi",
    "name": "下垣内洋一",
    "kana": "しもがいち　よういち",
    "origin": "生え抜き（1958年入社）。鉄鋼営業・企画畑で、副社長・鉄鋼事業本部長としてリストラを主導してから社長へ",
    "origin_type": "生え抜き",
    "hometown": "東京都",
    "education": "東京大学法学部 (1958)",
    "prev_role": "副社長・鉄鋼事業本部長",
    "birthdate": "1934",
    "career": [
      {
        "company": "日本鋼管",
        "from": "1958-04",
        "to": null,
        "roles": [
          {
            "date": "1958-04",
            "role": "入社"
          },
          {
            "date": "1981",
            "role": "営業総括部長"
          },
          {
            "date": "1986",
            "role": "綜合企画部長"
          },
          {
            "date": "1987",
            "role": "取締役"
          },
          {
            "date": "1989",
            "role": "常務"
          },
          {
            "date": "1991",
            "role": "専務"
          },
          {
            "date": "1994",
            "role": "副社長・鉄鋼事業本部長"
          },
          {
            "date": "1997-06",
            "role": "社長",
            "is_ceo_appointed": true
          },
          {
            "date": "2002-02",
            "role": "社長退任",
            "is_ceo_retired": true,
            "retirement_basis": "press"
          },
          {
            "date": "2002-02",
            "role": "会長"
          }
        ]
      }
    ],
    "references": [
      {
        "source": "日経ビジネス 1998年1月5日号 p76-77 新社長登場 下垣内洋一氏",
        "for": [
          "kana",
          "career",
          "education",
          "hometown",
          "birthdate",
          "origin"
        ]
      },
      {
        "source": "日経ビジネス 2002年1月7日号 p18-19 2002年社長人事予想",
        "for": [
          "career"
        ]
      }
    ],
    "html_url": "https://the-shashi.com/tse/5404/executives/ceo/shimogaichi-yoichi/",
    "term_start": "1997-06",
    "term_end": "2002-02",
    "api_url": "https://the-shashi.com/api/5404/ceo/shimogaichi-yoichi.json",
    "list_api_url": "https://the-shashi.com/api/5404/ceo.json",
    "predecessor": {
      "slug": "miyoshi-shunkichi",
      "name": "三好俊吉",
      "api_url": "https://the-shashi.com/api/5404/ceo/miyoshi-shunkichi.json"
    },
    "successor": {
      "slug": "hammyo-masayuki",
      "name": "半明正之",
      "api_url": "https://the-shashi.com/api/5404/ceo/hammyo-masayuki.json"
    }
  }
}