To provide an engine starting system capable of surely starting an engine and securing the reliability of a vehicle as a whole.

In an economical running vehicle, as the engine 1 is automatically stopped when the vehicle is stopped by a signal at an intersection, the number of times of starting the engine is remarkably increased in comparison with ordinary vehicles. Thereby a temperature of a starter is raised by the heat generated from a motor part of a main starter 2, a switch coil and the like, when the connecting and disconnecting operation (ON/OFF) of the main starter 2 is repeated several times in a short time. Thus, the temperature of the starter is detected by a temperature sensor 9, and the main starter 2 is switched to an auxiliary starter 3 to start the engine when an output value of the sensor is more than a predetermined temperature. Thereby the running of the vehicle becomes available, thus enabling to prevent the failure of the main starter 2 caused by the thermal deterioration of the motor part of the main starter 2, the switch coil and the like.