Abstract: A safety system is disclosed for universal attachment to existing garage door openers. A transmitter of infrared energy transmits a beam laterally of the door opening to detect any obstruction to door closing movement. A safety control circuit is adapted for connection to the main control circuit of the existing garage door opener, the existing push button switch is disconnected from the main control circuit and connected to the new safety control circuit, a flexible cable or cord is connected for actual movement in accordance with movement of the door and is connected to the safety control circuit at a reel on which the cord is wound, and the safety control circuit determines if there is actual door movement and actual door closing movement, as well as being responsive to an obstruction to door closing movement to apply a signal to stop the door and then apply another signal to start the door in its opening movement.