1920 in Japan

Incumbents

• Emperor: Taishō
• Prime Minister: Hara Takashi

  Events

• January 10 - Japan is a founding member of the League of Nations.
• January 30 - Mazda founded, as predecessor name was Toyo Cork Industry.
• February Unknown date - Kawanishi Engineering Works, as predecessor of ShinMaywa, is founded in Hyogo-ku, Kobe.
• February 1 - Japanese sugar plantation workers in Hawaii officially join a strike led by Filipinos and Hispanic workers.
• February 24 - Nikolayevsk Incident: Realizing that he is outnumbered and far from reinforcement, the commander of the Japanese garrison allowed Yakov Triapitsyn's troops to enter the town of Nikolayevsk-on-Amur under a flag of truce.
• May 10 - In the general election, the Rikken Seiyūkai, led by Prime Minister Hara Takashi, increases on its majority of seats in the lower house of the Diet.
• June - About 450 Japanese civilians and 350 Japanese soldiers, along with Russian White Army supporters, are massacred by partisan forces associated with the Red Army at Nikolayevsk on the Amur River.
• June Unknown date - Shikishima Bakery was founded in Nagoya, as predecessor of Pasco Shikishima.
• September 1 - Rinnai was founded in Nagoya.
• September 17 - The Victory Medal, a commemorative military medal of Japan awarded to mark service during the First World War, is established by Imperial Edict.
• October 21 - The Battle of Qingshanli begins between the Imperial Japanese Army and Korean armed groups in a densely wooded region of eastern Manchuria called Qīngshānlǐ.
• date unknown
• *The literary magazine Teikoku Bungaku is published for the last time.
• *The Guards Cavalry Regiment, Guards Field Artillery Regiment, Guards Engineer Battalion, Guards Transport Battalion, plus other Guards service units are added to the Japanese Imperial Guard.

  Births

• January 23 - Nejiko Suwa, violinist
• January 30 - Machiko Hasegawa, Illustrator
• March 17 - Takeo Doi, academic, psychoanalyst and author
• March 22 - Katsuko Saruhashi, geochemist
• April 1 - Toshiro Mifune, actor
• May 9 - Mitsuko Mori, actress
• May 30 - Shōtarō Yasuoka, writer
• June 17 - Setsuko Hara, actress
• July 15 - Yoshio Inaba, actor
• October 20 - Masao Sugiuchi, go player
• December 24 - Hiroyuki Agawa, writer

  Deaths

• January 10 - Yoshikawa Akimasa, politician and cabinet minister
• January 11 - Kataoka Shichirō, admiral
• April 12 - Takaki Kanehiro, naval physician
• April 27 - Tadashi Satō, soldier and politician
• September 20 - Shō Ten, last Ryūkyū crown prince, member of the House of Peers
• October 5 - Suematsu Kenchō, politician and author
• October 6 - Kuroiwa Shūroku, journalist and writer