The 1954–55 Tercera División season was the 19th since its establishment.
164 teams competed in 16 geographic groups. For the first time there were North African and Balearic Islands groups.
Promotion:Each group winner and runner-up (32 teams) progressed to the Fase Final where 4 groups of 8 teams were formed. The four group winners were promoted to the Segunda División.
Relegation The remaining teams in the geographic groups were joined by teams from the fourth tier - the Regional leagues - to contest places in the following season's Tercera División.
Note: RCD Mallorca qualified for the Fase Final. Runners-up Constancia played-off against the Menorca sub-group winners for the second spot in the Fase Final.
Note: Maó qualified for a play-off against the Mallorca sub-group runners-up.