Selective growth of GaAs using a graphene mask was investigated. While selective growth with a SiO2 mask required a temperature of more than 620°C, the critical temperature required with the graphene mask was as low as 600°C, which is ascribed to the weak bonding characteristics between the graphene mask and the adatoms on the growth surface. The mechanism of selective growth was examined with systematic change of the growth temperature, and the activation energy for selective growth was evaluated. Selective growth with a patterned graphene mask provided excellent selectivity and a very flat and smooth GaAs layer was obtained.