This is the list of number-one singles in Japan during 1991 according to Oricon Chart[1]
| Issue Date | Song | Artist | |
|---|---|---|---|
| January 7 | (No information) | ||
| January 14 | "Ai wa Katsu" (愛は勝つ) | Kan | |
| January 21 | |||
| January 28 | |||
| February 4 | |||
| February 11 | |||
| February 18 | "Oh | Yeah!/Love Story wa Totsuzen ni" | Kazumasa Oda |
| February 25 | |||
| March 4 | |||
| March 11 | |||
| March 18 | |||
| March 25 | |||
| April 1 | |||
| April 8 | "Lady Navigation" | B'z | |
| April 15 | |||
| April 22 | "Wednesday Moon" | Hideaki Tokunaga | |
| April 29 | "Lady Navigation" | B'z | |
| May 6 | "Eyes to Me" | Dreams Come True | |
| May 13 | |||
| May 20 | "Kiss" | Princess Princess | |
| May 27 | "Please" | Shizuka Kudo | |
| June 4 | "Love Train" | TMN | |
| June 10 | "Anata ni aete yokatta" (あなたに会えてよかった) | Kyōko Koizumi | |
| June 17 | |||
| June 24 | |||
| July 1 | |||
| July 8 | "Beat Emotion" | Tomoyasu Hotei | |
| July 15 | "Anata ni aete yokatta" (あなたに会えてよかった) | Kyōko Koizumi | |
| July 22 | "Neo Bravo! | " | Southern All Stars |
| July 29 | "Donna Toki Mo." (どんなときも) | Noriyuki Makihara | |
| August 5 | "Say Yes" | Chage and Aska | |
| August 12 | |||
| August 19 | |||
| August 26 | |||
| September 2 | |||
| September 9 | |||
| September 16 | |||
| September 23 | |||
| September 30 | |||
| October 7 | |||
| October 14 | |||
| October 21 | |||
| October 28 | |||
| November 4 | "Shabontama" (しゃぼんたま) | Tsuyoshi Nagabuchi | |
| November 11 | "Alone" | B'z | |
| November 18 | |||
| November 25 | "Wild Heaven" | TMN | |
| December 2 | "Boku wa kono hitomi de usowotsuku" (僕はこの瞳で嘘をつく) | Chage and Aska | |
| December 9 | "Piece of My Wish" | Miki Imai | |
| December 16 | |||
| December 23 | |||
| December 30 | "Sore ga Daiji" (それが大事) | Daiji-man Brothers Band |