List of Oricon number-one singles of 1978
# List of Oricon number-one singles of 1978

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 1978.

## Oricon Weekly Singles Chart

| Issue date | Song | Artist(s) |
| - | - | - |
| January 2 | "UFO" | Pink Lady |
| January 9 | "UFO" | Pink Lady |
| January 16 | "UFO" | Pink Lady |
| January 23 | "UFO" | Pink Lady |
| January 30 | "UFO" | Pink Lady |
| February 6 | "UFO" | Pink Lady |
| February 13 | "UFO" | Pink Lady |
| February 20 | "UFO" | Pink Lady |
| February 27 | "Canada Kara no Tegami [ja]" | Masaaki Hirao [ja] & Yōko Hatanaka [ja] |
| March 6 | "Canada Kara no Tegami [ja]" | Masaaki Hirao [ja] & Yōko Hatanaka [ja] |
| March 13 | "Hohoemi Gaeshi" | Candies |
| March 20 | "Hohoemi Gaeshi" | Candies |
| March 27 | "Hohoemi Gaeshi" | Candies |
| April 3 | "Southpaw" | Pink Lady |
| April 10 | "Southpaw" | Pink Lady |
| April 17 | "Southpaw" | Pink Lady |
| April 24 | "Southpaw" | Pink Lady |
| May 1 | "Southpaw" | Pink Lady |
| May 8 | "Southpaw" | Pink Lady |
| May 15 | "Southpaw" | Pink Lady |
| May 22 | "Southpaw" | Pink Lady |
| May 29 | "Southpaw" | Pink Lady |
| June 5 | "Darling [ja]" | Kenji Sawada |
| June 12 | "Jikan yo Tomare [ja]" | Eikichi Yazawa |
| June 19 | "Jikan yo Tomare [ja]" | Eikichi Yazawa |
| June 26 | "Jikan yo Tomare [ja]" | Eikichi Yazawa |
| July 3 | "Mr. Summertime [ja]" | Circus [ja] |
| July 10 | "Monster" | Pink Lady |
| July 17 | "Monster" | Pink Lady |
| July 24 | "Monster" | Pink Lady |
| July 31 | "Monster" | Pink Lady |
| August 7 | "Monster" | Pink Lady |
| August 14 | "Monster" | Pink Lady |
| August 21 | "Monster" | Pink Lady |
| August 28 | "Monster" | Pink Lady |
| September 4 | "Hikigane [ja]" | Masanori Sera & Twist [ja] |
| September 11 | "Kimi no Hitomi wa 10,000 Volt [ja]" | Takao Horiuchi |
| September 18 | "Kimi no Hitomi wa 10,000 Volt [ja]" | Takao Horiuchi |
| September 25 | "Kimi no Hitomi wa 10,000 Volt [ja]" | Takao Horiuchi |
| October 2 | "Tomei Ningen" | Pink Lady |
| October 9 | "Kimi no Hitomi wa 10,000 Volt" | Takao Horiuchi |
| October 16 | "Tomei Ningen" | Pink Lady |
| October 23 | "Tomei Ningen" | Pink Lady |
| October 30 | "Tomei Ningen" | Pink Lady |
| November 6 | "Kisetsu no Naka de [ja]" | Chiharu Matsuyama |
| November 13 | "Kisetsu no Naka de [ja]" | Chiharu Matsuyama |
| November 20 | "Kisetsu no Naka de [ja]" | Chiharu Matsuyama |
| November 27 | "Kisetsu no Naka de [ja]" | Chiharu Matsuyama |
| December 4 | "Kisetsu no Naka de [ja]" | Chiharu Matsuyama |
| December 11 | "Kisetsu no Naka de [ja]" | Chiharu Matsuyama |
| December 18 | "Chameleon Army" | Pink Lady |
| December 25 | "Chameleon Army" | Pink Lady |
