A semiconductor device includes a semiconductor substrate on which a first insulation film is provided. A first conductive film is on the first insulation film. First electrode films are on the first conductive film and stacked. A charge accumulation member is between one of the first electrode films and the semiconductor member. The first conductive film includes a main body arranged below the first electrode films and an outer peripheral portion provided in an outer periphery of the main body to be apart from the main body. First and second slits are alternately provided in the outer peripheral portion, and extend along the outer periphery of the main body. The first and second slits are apart from each other as viewed in the stacking direction, and partly overlap each other as viewed in a first direction directed from the main body toward the outer peripheral portion.