In the engine starter related to the present invention, a torsional angle θ1 of a helical spline 4a of an output shaft 4 is set in such a way that a reactive force Fp1 of a plunger spring 33, which is operated to a clutch 5, is larger than a propulsive force F, which is operated so as to extrude the clutch 5 by a rotational force of the motor 2 in a shaft direction along a helical spline 4a of an output shaft 4, before a pinion extruding solenoid 8 is operated. Thereby, it can be prevented that the clutch 5 is extruded in the shaft direction, so that it can be prevented without upsizing the engine starter that the pinion 6 is protruded in the shaft direction.