PURPOSE: To simplify a configuration by providing a micro-computer within a receiver with a pass word coincidence judging means which is connected with No.1 input terminal of the computer, and thereby changing the pass word code of a memory means to the pass word code inputted to No.2 input terminal.

CONSTITUTION: Pass word codes are set in a transmitter 1, the pass word code is read out every time when a transmitting button 2 on the upper surface depressed so as to be inputted into the receiver 10 of a vehicle by, for example, infra-red ray signals. The receiver 10 includes a photo diode 12 the output of which is inputted to No.1 input terminal 17a of a micro-computer 17 via an inputting means 13. The micro-computer 17 includes a code memory means 18 storing pass word codes, a code changing means 19 and a coincidence judging means 20, and a door lock motor 22 is driven when the input value of the pass word code is consistent with the stored value. When the pass word is reloaded, the pass word code is transmitted while the transmitter 1 is drawn close to the receiver 10, and signals are thereby inputted to No.2 input terminal 17a so that the pass word code is reloaded.