The 1955–56 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, Sparta and Strømmen promoted directly to the 1956–57 Hovedserien.
The other five group winners qualified for promotion play-offs to compete for two spots in the following season's top flight.
Årstad and Steinkjer won the play-offs and were promoted.