A semiconductor device includes a first semiconductor substrate, a first insulating film provided at the first semiconductor substrate and including a first recess portion on a surface portion thereof, a first metal film provided at the first recess portion and having a first surface exposed from the first insulating film, a second semiconductor substrate, a second insulating film provided at the second semiconductor substrate and including a second recess portion on a surface portion thereof, a second metal film provided at the second recess portion and having a second surface exposed from the second insulating film, first anti-diffusion films, and second anti-diffusion films provided at outer circumferential portions of the first anti-diffusion films. The second surface is joined to the first surface. The first anti-diffusion films are provided at the first recess portion and the second recess portion and cover the first metal film and the second metal film.