A remote control security apparatus includes a lock element movable between locked and unlocked positions by an electrically actuated power device. The operator is provided with a portable transmitter adapted to generate light which is interrupted at a predetermined frequency so as to produce an encoded light signal. This signal is detected by a light transceiver which generates an independent signal at the same predetermined frequency and which compares the frequencies of the detected signal and independent signal. If these frequencies are substantially the same, the transceiver actuates the power means to move the lock element to its unlocked position. The security apparatus may be advantageously installed as a door lock, in which case a lock element receiving member is secured to the door. The signal detector is positioned at the exterior side of the door for receiving encoded signals from the transmitter and an override switch may be positioned at an interior side of the door for opening the lock without a transmitter. A contact switch is disclosed which maintains the lock element in the unlocked position whenever the door is open
