Gjerdrum is a municipality in Akershus county, Norway. It is part of the traditional region of Romerike.Gjerdrum was established as a municipality on 1 January 1838 (see formannskapsdistrikt).Gjerdrum borders the municipalities of Nannestad, Nittedal, Ullensaker, Skedsmo, and Sørum. The administrative centre of the municipality is the village of Ask.
The municipality (originally the parish) is named after the old Gjerdrum farm (Norse Gerðarvin). The first element is the genitive of a river name Gerð and the last element is vin f 'meadow, pasture'. The river name is derived from the Norse word garðr meaning 'fence' and so the meaning is 'the river whose function is a fence (and/or as a border)'.