This invention relates to dust-proof, moisture-proof structures of the image pickup devices mounted in small-size thin types of electronic apparatus. More specifically, an image pickup device of this invention includes an image pickup element, a mounting base having a formed leg section which abuts on the image pickup element, an image pickup optical system that guides photographic object light to the imaging region of the image pickup element, and an outer frame member that contains the image pickup element, the mounting base, and the image pickup optical system. The space formed at the photoelectric conversion plane side of the image pickup element is sealed by using the mounting base or by using the mounting base and a part of the outer frame member.