A remote control transmitter used for a switching of a state of a door lock device between a locked state and an unlocked state and so on comprises a portable-size case, operating buttons provided on an outer surface of the case, a secondary battery provided within the case, a solar battery provided on the outer surface of the case and rechargeably connected to the secondary battery, and a generator for generating a coded signal. One terminal of each operating button is connected to a positive terminal of the secondary battery and the other terminal is connected to a positive terminal of the generator. When one of the operating buttons is pushed, electric current is fed from the secondary battery to the generator.