List of Oricon number-one singles of 1985
The highest-selling singles in Japan are ranked in the Oricon Singles Chart, which is published by Oricon Style magazine. The data are compiled by Oricon based on each singles' physical sales. This list includes the singles that reached the number one place on that chart in 1985.
Oricon Weekly Singles Chart
| Issue date | Song | Artist | Ref. |
| January 7 | "" | Kyōko Koizumi | |
| January 14 | "" | Kyōko Koizumi | |
| January 21 | "" | Kōji Kikkawa | |
| January 28 | "" | Kōji Kikkawa | |
| February 4 | "" | Kōji Kikkawa | |
| February 11 | "" | Seiko Matsuda | |
| February 18 | "" | Seiko Matsuda | |
| February 25 | "Yoisho!" | Masahiko Kondō | |
| March 4 | "" | The Alfee | |
| March 11 | "" | Momoko Kikuchi | |
| March 18 | "" | Akina Nakamori | |
| March 25 | "" | Akina Nakamori | |
| April 1 | "" | The Checkers | |
| April 8 | "" | The Checkers | |
| April 15 | "" | The Checkers | |
| April 22 | "" | Kyōko Koizumi | |
| April 29 | "" | Kyōko Koizumi | |
| May 6 | "" | Kōji Kikkawa | |
| May 13 | "" | Akina Nakamori | |
| May 20 | "" | Seiko Matsuda | |
| May 27 | "" | Momoko Kikuchi | |
| June 3 | "" | Momoko Kikuchi | |
| June 10 | "" | Yumi Matsutoya, Kazumasa Oda, | |
| June 17 | "" | Yumi Matsutoya, Kazumasa Oda, | |
| June 24 | "" | Naoko Kawai | |
| July 1 | "" | Akina Nakamori | |
| July 8 | "" | Seiko Matsuda | |
| July 15 | "" | The Checkers | |
| July 22 | "" | The Checkers | |
| July 29 | "" | The Checkers | |
| August 5 | "" | Kyōko Koizumi | |
| August 12 | "" | Anzen Chitai | |
| August 19 | "" | Anzen Chitai | |
| August 26 | "" | Toshihiko Tahara | |
| September 2 | "Kanashimi ni Sayonara" | Anzen Chitai | |
| September 9 | "Kanashimi ni Sayonara" | Anzen Chitai | |
| September 16 | "" | Sonoko Kawai | |
| September 23 | "" | Sonoko Kawai | |
| September 30 | "" | The Checkers | |
| October 7 | "" | Momoko Kikuchi | |
| October 14 | "" | Momoko Kikuchi | |
| October 21 | "" | Akina Nakamori | |
| October 28 | "" | Akiko Kobayashi | |
| November 4 | "" | Akiko Kobayashi | |
| November 11 | "" | The Checkers | |
| November 18 | "Koi ni Ochite: Fall in Love" | Akiko Kobayashi | |
| November 25 | "Koi ni Ochite: Fall in Love" | Akiko Kobayashi | |
| December 2 | "" | Kyōko Koizumi | |
| December 9 | "Koi ni Ochite: Fall in Love" | Akiko Kobayashi | |
| December 16 | "Koi ni Ochite: Fall in Love" | Akiko Kobayashi | |
| December 23 | "" | Shonentai | |
| December 30 | "Koi ni Ochite: Fall in Love" | Akiko Kobayashi | |
| - | - | - |