An interrupter includes: a light emitting device; a light receiving device placed at a position on which light emitted from the light emitting device can be incident; and a mold member made of a material that transmits part of the light and absorbs the rest, including a section enclosing the light emitting device and a section enclosing the light receiving device, and having a gap between the light emitting device and the light receiving device. At least one of the thickness of the section of the mold member enclosing the light emitting device and the thickness of the section of the mold member enclosing the light receiving device is relatively thin in a region intervening in a linear light path from the light emitting device to the light receiving device, and is relatively thick in a surrounding region around said region.