The invention is directed to a system for detecting the presence of a child in a car, when the driver exits the vehicle. A sensor is connected to the seat belt of the baby's car seat or to the rear seat belts. Once the seat belt is inserted into the belt buckle, an alarm circuit is activated. When the driver enters the vehicle and sits down, the system detects the presence of the driver and de-activates the alarm circuit. When the driver exits, the alarm circuit is then re-activated. The system includes a delay timer that gives the driver time to enter and exit the vehicle without setting off the alarm circuit. When the alarm circuit is activated, a timer for the time delay begins. At the end of the time delay (e.g., relay is transferred), if the driver has not disabled the alarm circuit by re-entering the vehicle or taking the child out of the vehicle, the alarm circuit will be set off warning signals and will remain energized until disabled.