To provide a starter having such a high versatility that can be used irrespective of a vehicle side structure, simply formed in structure, and capable of accurately determining the state of a switch.

When a starter 1 line is necessary, it is connected to the starter switch SWs1. When the starter 1 line is not necessary, it is connected to a starter line 2 through an auxiliary circuit 18. Also, when the starter 1 line is not necessary, a determination timing for the starter switch SWs1 is changed to align it with the determination timing of the starter switch SWs2 so as to virtually realize the determination for a switch not present.