An electromagnetic switch device for a starter includes a pinion-pushing solenoid for pushing out a pinion toward a ring gear of an engine by a plunger thereof, and a motor-energizing solenoid for energizing the motor. The electromagnetic switch device is configured to detect a magnetic flux change in a magnetic circuit of the motor-energizing solenoid due to displacement or deformation of a core of the motor-energizing solenoid caused when the plunger of the pinion-pushing solenoid abuts against a stopper, to determine a timing to start current supply to the motor-energizing solenoid.