There is disclosed a power door lock system for use with an automobile, The lock system comprises an actuator for locking or unlocking a door or the tailgate, a microcomputer, a key code transmitter mounted on the vehicle, a key code receiver connected with the microcomputer, a nonvolatile memory in which a key code is stored, timers connected with the microcomputer, a passenger-detecting circuit, and a switch that is closed when the door is completely closed. The microcomputer includes a comparator for comparing the key code detected by the key code receiver with the key code stored in the memory. The operation of the actuator is controlled by the microcomputer to prevent malfunction.