A remote control transmitter includes a transparent protective filter that covers a light emitting device in the light emitting direction. The filter is formed as a strip shaped, long and thin plate that is made from a transparent material that has a refractive index that is larger at least than that of air. The transparent protective filter, is attached so that it is oriented frontwards from the front surface of the case so that one end surface in the longitudinal directions opposes the light emitting device. The optical control signal that is emitted from the light emitting device is emitted from another end surface of the transparent protective filter, such that the optical control signal is not blocked by the finger that grasps the case, even if that case is formed with a size such that it can be grasped with one hand.