The 1956–57 Landsdelsserien was a Norwegian second-tier football league season.
The league was contested by 54 teams, divided into a total of seven groups from four districts; Østland/Søndre, Østland/Nordre, Sørland/Vestre and Møre/Trøndelag.
[1] The two group winners in the Østland districts, Eik and Raufoss promoted directly to the 1957–58 Hovedserien.
The other five group winners qualified for promotion play-offs to compete for two spots in the following season's top flight.
Brann and Molde won the play-offs and were promoted.