Events in the year 1998 in Japan. It corresponds to the year Heisei 10 (平成10年) in the Japanese calendar.

• Emperor: Akihito^[1]
• Prime Minister: Ryutaro Hashimoto (L–Okayama) until July 30, Keizo Obuchi (L–Gunma)
• Chief Cabinet Secretary: Kanezō Muraoka (L–Akita) until July 30, Hiromu Nonaka (L–Kyōto)
• Chief Justice of the Supreme Court: Shigeru Yamaguchi
• President of the House of Representatives: Sōichirō Itō (L–Miyagi)
• President of the House of Councillors: Jūrō Saitō (L–Mie) until July 25 and again from August 4
• Diet sessions: 142nd (regular, January 12 to June 18), 143rd (extraordinary, August 7 to October 16), 144th (extraordinary, November 27 to December 14)

• February 7 – February 22: The 1998 Winter Olympics are held in Nagano.^[2]
• March 5 – March 14: The 1998 Winter Paralympics are held in Nagano.^[2]
• April 1: Toyota City, Fukuyama City, Kōchi City and Miyazaki City become core cities.
• April 5: The Akashi-Kaikyo Bridge linking Shikoku with Honshū and costing about ¥ 500 billion (US$3.8 billion), opens to traffic, becoming the largest suspension bridge in the world.^[3]
• May 26: Takashi Imai is inaugurated as the 9th head of the Keidanren.
• June 22: Financial Services Agency established.
• July 5: Japan launches the Nozomi probe to Mars, joining the United States and Russia as an outer space-exploring nation.
• July 12: Election for the House of Councillors held.
• July 25: Masumi Hayashi poisons a curry pot at a festival in Wakayama, causing the death of two adults and two children.
• September 3: Metal Gear Solid is first released for the PS1 in Japan.
• September 7 1998: Serial Experiments Lain Episode 10 : LOVE is released in [J]apan.
• September 22 – 23: Typhoon Vivki causes damage to several cultural heritage sites in Wakayama, Nara, Kyoto and Shiga Prefecture and causing 19 deaths.^{[citation needed]}
• October 8: Japan-South Korea Joint Declaration of 1998.
• November 13: Free solo climber Alain Robert scales the Shinjuku Center Building and is arrested on its roof.
• November 26: Japan-China Joint Declaration On Building a Partnership of Friendship and Cooperation for Peace and Development.
• December 18: Mario Party is released in Japan.

• January 5 - Marie Iitoyo, model and actress
• January 23 - Yuto Adachi, singer and member of South Korean boy band Pentagon
• February 8 - Rui Hachimura, basketball player
• March 19 - Sakura Miyawaki, singer and member of South Korean girl group Le Sserafim
• March 26 - Satoko Miyahara, figure skater
• April 6 - Rina Katsuta, singer
• April 10 - Airi Kinoshita, murder victim (d. 2005)
• April 28 - Manamo Miyata, singer and member of Hinatazaka46
• May 13 - Karen Iwata, singer and voice actress
• May 28 - Riho Sayashi, J-pop singer
• May 31 - Ryang Hyon-ju, North Korean, footballer
• June 14 - Taishi Nakagawa, actor and model
• June 19 - Suzu Hirose, model and actress
• July 9 - Tiger Onitsuka, jazz drummer
• July 16 - Rina Matsuno, singer (d. 2017)
• July 17 - Shione Sawada, actress
• July 26 - Maya Sakura, singer
• July 27 - Risa Watanabe, idol and model
• August 5 - Kanon Suzuki, singer
• August 17 - Yoshinobu Yamamoto, professional baseball player
• August 28 - Haruka Fukuhara, actress, model and singer
• October 30 - Meimi Tamura, singer and actress
• November 12 - Yuna Taira, actress
• November 29 - Ayumu Hirano, snowboarder
• December 24 - Keito Tsuna, actor
• December 30 - Akari Uemura, pop singer

• January 9 – Kenichi Fukui, Japanese chemist, Nobel Prize laureate (b. 1918)
• January 21 – Yoshifumi Kondō, animator (b. 1950)
• January 26 – Shinichi Suzuki, violinist (b. 1898)
• January 27 – Tamio Kageyama, novelist (b. 1947)
• January 28 – Shotaro Ishinomori, Manga artist, "Father of Henshin heroes." (b. 1938)
• February 5 – Takahashi Chikuzan, Tsugaru-jamisen performer and composer (b. 1910)
• March 10 – Kenkō Satoshi, Sumo wrestler (b. 1967)
• March 13 – Kosho Uchiyama, Sōtō priest (b. 1912)
• April 20 – Yoshio Inaba, actor (b. 1920)
• May 2 – Matsumoto Hideto (hide), Japanese musician (b. 1964)
• May 10 – Nekojiru, manga artist (b. 1967)
• May 19 – Sōsuke Uno, Prime Minister (b. 1922)
• August 3 – Reizo Koike, breaststroke swimmer (b. 1915)
• August 28 – Hirokazu Kobayashi, aikidoka (b. 1929)
• September 6 – Akira Kurosawa, screenwriter, producer, and director (b. 1910)
• September 27 – Narita Bryan, racehorse (b. 1991)
• October 12 – Ineko Sata, communist and feminist author of proletarian literature (b. 1904)
• November 1 – Silence Suzuka, racehorse (b. 1994)
• November 5 – Momoko Kōchi, actress (b. 1932)
• December 1 – Shōji Nakayama, actor (b. 1928)
• December 2 – Mikio Oda, athlete (b. 1905)
• December 30 – Keisuke Kinoshita, film director (b. 1912)

• 1998 in Japanese television
• List of Japanese films of 1998