1942 in Japan

• Emperor: Hirohito^[1]
• Prime Minister: Hideki Tōjō

• Aichi Prefecture: Yukisawa Chiyoji
• Akita Prefecture: Fumi
• Aomori Prefecture: Seiichi Ueda (until 9 June); Shunsuke Yamada (starting 9 June)
• Ehime Prefecture: Masatomi Hatakeda (until 7 July); Ryuichi Fukumoto (starting 7 July)
• Fukui Prefecture:
  • until 9 January: Kubota
  • 9 January-15 June: Shigeo Miyoshi
  • starting 15 June: Nagano Wakamatsu
• Fukushima Prefecture: Sumio Hisakawa (until 7 July); Yoshio Araki (starting 7 July)
• Gifu Prefecture: Tetsushin Sudo (until 23 May); Miyoshi Shigeo (starting 23 May)
• Gunma Prefecture: Goro Murata
• Hiroshima Prefecture: Tokiji Yoshinaga (until 15 June); Saiichiro Miyamura (starting 15 June)
• Ibaraki Prefecture: Kanichi Naito (until 7 October); Tsujiyama (starting 7 October)
• Iwate Prefecture: Yoshifumi Yamauchi (until 15 June); Osamuzo Suzuki (starting 15 June)
• Kagawa Prefecture: Osamu Eianhyaku (until 9 January); Yoshiji Kosuga (starting 9 January)
• Kanagawa Prefecture: Mitsuma Matsumura (until month unknown)
• Kochi Prefecture: Naoaki Hattori (until 7 July); Satoru Okino (starting 7 July)
• Kumamoto Prefecture: Chioji Yukisawa (until 10 June); Hikari Akira (starting 10 June)
• Kyoto Prefecture: Ando Kyoushirou
• Mie Prefecture: Yoshiro Nakano (until 7 October); Koji Soga (starting 7 October)
• Miyagi Prefecture: Nobuo Hayashin (until 7 October); Otomaru Kato (starting 7 October)
• Miyazaki Prefecture: Osafume Katsumi
• Nagano Prefecture: Noburo Suzuki (until 9 January); Nagoya Osamu (starting 9 January)
• Niigata Prefecture: Doi Shohei
• Oita Prefecture: Ito Hisamatsu (starting 6 May)
• Okinawa Prefecture: Hajime Hayakawa
• Saga Prefecture: Yue Yue [ja] (until 23 May); Shogo Tanaka (starting 23 May)
• Saitama Prefecture: Miyano Shozo (until 9 January); Toshio Otsu (starting 9 January)
• Shiname Prefecture: Yasuo Otsubo (until 9 January); Goro Koizumi (starting 9 January)
• Tochigi Prefecture: Saburo Yamagata (until 9 January); Sakurai Yasuemon (starting 9 January)
• Tokyo: Jitsuzo Kawanishi (until 9 January); Matsumura Miro (starting 9 January)
• Toyama Prefecture: Kingo Machimura
• Yamagata Prefecture: Hee Yamauchi (until 7 July); Akira Saito (starting 7 July)

Below, events of World War II have the "WWII" preface

• 11 January – Japanese paratroopers land on Sulawesi.
• 12 January – Japan declares war on the Dutch.
• 22 January – Hideki Tōjō warns Australia that "if you continue resistance, we Japanese will destroy you."
• 4 February – Japan demands the surrender of Singapore.
• 17 February – Singapore is renamed Shōnan ("Light of the South").
• 20 March – The navy minister, Admiral Shigetarō Shimada says that in view of the Allies' "Retaliation and hatred", Japan would no longer follow recognized rules of sea warfare.
• 18 April – Doolittle Raid, the first bombing raid on the Japanese home islands
• 25 May – Four ships leave Hokkaido to stage a diversionary raid on the Aleutian Islands.
• 4–7 June – Battle of Midway
• 21 August – Battle of the Tenaru
• 11–12 October – Battle of Cape Esperance
• 12–15 November – Naval Battle of Guadalcanal

• January 8 – Junichiro Koizumi, 56th Prime Minister of Japan
• January 27 – Tasuku Honjo, immunologist
• February 1 – Masa Saito, professional wrestler (d. 2018)
• March 17 – Yoko Yamamoto, actress (d. 2024)^[2]
• March 29 – Kenichi Ogata, actor
• April 2 – Hiroyuki Sakai, chef
• April 25 – Katsuji Adachi, professional wrestler (d. 2010)
• May 24 – Ichirō Ozawa, politician
• July 3 – Mitsuhiro Kitta, golfer
• July 5 – Motoaki Inukai, footballer
• July 22 – Toyohiro Akiyama, astronaut
• August 31 – Isao Aoki, golfer
• September 16 – Tadamasa Goto, yakuza boss
• September 19 – Nobuo Sekine, sculptor (d. 2019)