A coaxial engine starter comprises an electric motor having an armature winding of a single turn and a hollow armature rotary shaft for generating a rotational force for starting an engine. The starter also comprises an over-running clutch mechanism disposed within the hollow armature rotary shaft for preventing the occurrence of an excessive-speed of the armature and having a pinion having a gear teeth number equal to or less than seven for engaging with a ring gear of an engine upon starting of the electric motor. A solenoid switch is also disposed behind the electric motor for moving a pinion shaft forward and supplying an electric power to the electric motor.
