| JSL Cup | |
| Year: | 1978 |
| Winners: | Furukawa Electric |
| Second: | Fujita Industries |
| Semifinal1: | Nippon Steel |
| Semifinal2: | Yomiuri |
| Prev Season: | 1977 |
| Next Season: | 1979 |
Statistics of JSL Cup in the 1978 season.
It was contested by 20 teams, and Mitsubishi Motors won the championship.
| Fujita Industries | Yomiuri | Hitachi | Fujitsu | Kofu | ||
| Fujita Industries | - | 1-3 | 2-1 | 2-1 | 4-2 | |
| Yomiuri | 3-1 | - | 4-0 | 2-4 | 1-1 (PK 3–2) | |
| Hitachi | 1-2 | 0-4 | - | 5-0 | 3-0 | |
| Fujitsu | 1-2 | 4-2 | 0-5 | - | 5-1 | |
| Kofu | 2-4 | 1-1 (PK 2–3) | 0-3 | 1-5 | - |
| Mitsubishi Motors | Furukawa Electric | Sumitomo Metals | Nissan Motors | Toshiba Horikawa | ||
| Mitsubishi Motors | - | 3-2 | 3-2 | 5-0 | 4-1 | |
| Furukawa Electric | 2-3 | - | 0-0 (PK 2–4) | 3-1 | 5-1 | |
| Sumitomo Metals | 2-3 | 0-0 (PK 4–2) | - | 1-1 (PK 4–5) | 3-1 | |
| Nissan Motors | 0-5 | 1-3 | 1 (PK 5–4)1 | - | 1-1 (PK 4–3) | |
| Toshiba Horikawa | 1-4 | 1-5 | 1-3 | 1-1 (PK 3–4) | - |
| Nippon Steel | Yanmar Diesel | Tanabe Pharmaceuticals | Teijin | Kyoto Shiko | ||
| Nippon Steel | - | 3-1 | 3-0 | 2-1 | 2-0 | |
| Yanmar Diesel | 1-3 | - | 2-0 | 5-1 | 5-0 | |
| Tanabe Pharmaceuticals | 0-3 | 0-2 | - | 2-0 | 1-0 | |
| Teijin | 1-2 | 1-5 | 0-2 | - | 6-0 | |
| Kyoto Shiko | 0-2 | 0-5 | 0-1 | 0-6 | - |
| Nippon Kokan | Honda | Toyo Industries | Yanmar Club | Toyota Motors | ||
| Nippon Kokan | - | 2-2 (PK 4–2) | 3-0 | 2-1 | 6-0 | |
| Honda | 2-2 (PK 2–4) | - | 1-1 (PK 3–4) | 3-1 | 6-2 | |
| Toyo Industries | 0-3 | 1-1 (PK 4–3) | - | 3-1 | 3-1 | |
| Yanmar Club | 1-2 | 1-3 | 1-3 | - | 1-0 | |
| Toyota Motors | 0-6 | 2-6 | 1-3 | 0-1 | - |
Mitsubishi Motors won the championship