Abstract: Obtained is an engine starter having a structure in which, even when frictional heat is generated on a roller due to sliding of a roller and a clutch inner with respect to each other, deformation of a rolling contact surface of the roller is reduced by suppressing reduction in hardness of the rolling contact surface of the roller due to the frictional heat, thereby making it possible to improve transmission of a rotation force from a clutch outer to a clutch inner. The engine starter includes a clutch (5) for transmitting a rotation force of an output shaft (4) to a pinion gear (7), a clutch outer (10), a clutch inner (11) having one end portion facing an inner portion of the clutch outer (10) and another end portion to which the pinion gear (7) is fixed, and a roller (12) which rolls while being provided between the clutch outer (10) and the clutch inner (11). The clutch outer (10) is formed with a notch portion (10a) of a tapered shape.

Abstract: Obtained is an engine starter having a structure in which, even when frictional heat is generated on a roller due to sliding of a roller and a clutch inner with respect to each other, deformation of a rolling contact surface of the roller is reduced by suppressing reduction in hardness of the rolling contact surface of the roller due to the frictional heat, thereby making it possible to improve transmission of a rotation force from a clutch outer to a clutch inner. The engine starter includes a clutch (5) for transmitting a rotation force of an output shaft (4) to a pinion gear (7), a clutch outer (10), a clutch inner (11) having one end portion facing an inner portion of the clutch outer (10) and another end portion to which the pinion gear (7) is fixed, and a roller (12) which rolls while being provided between the clutch outer (10) and the clutch inner (11). The clutch outer (10) is formed with a notch portion (10a) of a tapered shape.