A portable transmitter is provided which transmits an operating instruction in the form of a radio wave to a controlled device which continues to operate while receiving the operating instruction. The portable transmitter includes a push switch and a touch sensor. The portable transmitter works to supply the electric power to the touch sensor for a given period of time in response to depression of the push switch. When the touch sensor senses a user's touch thereon, and the push switch is depressed, the portable transmitter transmits the operating instruction to the controlled device and continues such transmission as long as the touch sensor senses the touch thereon regardless of the depression of the push switch. In other words, once the operating instruction has been outputted to the controlled device, the user is required only to touch the touch sensor in order to make the controlled device continue the operation.