A method of depositing a thin film includes: repeating a first gas supply cycle a first plurality of times, the first gas supply cycle including supplying a source gas to a reaction space; supplying first plasma while supplying a reactant gas to the reaction space; repeating a second gas supply cycle a second plurality of times, the second gas supply cycle including supplying the source gas to the reaction space; and supplying second plasma while supplying the reactant gas to the reaction space, wherein the supplying of the first plasma includes supplying remote plasma, and the supplying of the second plasma includes supplying direct plasma.