Abstract: A car door safety device is formed by serially connecting a car-door-opened alarm device with an alarm switch and then is parallelly connected to an ignition control circuit. Two ends thereof being connected to a positive and negative polarities of a power source. The ignition control circuit is formed by a single shooting switch, a ignition control switch and a high voltage ignition coil. The ignition control switch includes a plurality of parallel-connected switches. When the car is being driven or is to be driven while the car door is not closed, other than the car-door-opened alarm device will be actuated to alert the driver, and the engine will turn off. Therefore, the present invention has the functions of promise and control so as to improve the safety of cars.