Disclosed is a passenger safety system for a vehicle that can remind a driver of the vehicle to check seats before leaving the vehicle. The system includes a control unit connected to an ignition sensor. The control unit can receive a signal from the ignition sensor indicating turning-off the ignition. The system may also include a weight sensor installed in the rear seat of the vehicle. The weight sensor is activated when an object is placed on the rear seat. The control unit can trigger an alert upon receiving a signal from the ignition sensor and the weight sensor is active. The alert can be an audio and/or visual alert for reminding the driver.