An electronic device includes a housing including an opening-portion and an annular-projection provided in the vicinity of the opening-portion from the housing, the annular-projection projecting so as to surround a periphery of the opening-portion, a frame member including a tubular-portion having an outer surface that faces the annular-projection to be fitted with the annular-projection, a top plate exposed from the opening-portion with the tubular-portion fitted with the annular-projection, an extension-portion extending from the outer surface of the tubular-portion, the tubular-portion being expanded toward the annular-projection when a pressing force is applied to a surface of the top plate exposed from the opening-portion with the annular-projection and the tubular-portion fitted with each other, and an O-ring that contacts entire peripheries of the outer surface of the tubular-portion and an inner surface of the annular-projection.