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 1980.
| Issue date | Song | Artist(s) | Ref. |
|---|---|---|---|
| January 7 | "Ihōjin" | Sayuri Kume | [1] |
| January 14 | |||
| January 21 | |||
| January 28 | "" | Crystal King | |
| February 4 | |||
| February 11 | |||
| February 18 | |||
| February 25 | |||
| March 3 | |||
| March 10 | "" | ||
| March 17 | |||
| March 24 | |||
| March 31 | |||
| April 7 | |||
| April 14 | |||
| April 21 | "" | Chanels | |
| April 28 | |||
| May 5 | |||
| May 12 | |||
| May 19 | |||
| May 26 | |||
| June 2 | |||
| June 9 | "" | ||
| June 16 | |||
| June 23 | |||
| June 30 | |||
| July 7 | |||
| July 14 | |||
| July 21 | |||
| July 28 | |||
| August 4 | |||
| August 11 | |||
| August 18 | "" | Tsuyoshi Nagabuchi | |
| August 25 | |||
| September 1 | |||
| September 8 | |||
| September 15 | |||
| September 22 | |||
| September 29 | "" | Toshihiko Tahara | |
| October 6 | |||
| October 13 | "" | Seiko Matsuda | |
| October 20 | |||
| October 27 | |||
| November 3 | |||
| November 10 | |||
| November 17 | "I'm In the Mood for Dancing" Japanese title: | The Nolans | |
| November 24 | |||
| December 1 | "" | Mayumi Itsuwa | |
| December 8 | |||
| December 15 | |||
| December 22 | "" | Masahiko Kondō | |
| December 29 |