PROBLEM TO BE SOLVED: To provide an alternating-current generator for a vehicle which increases the air capacity of cooling air to improve the cooling effect.SOLUTION: An alternating-current generator 1 includes: a casing 4 having a vent hole at its outer periphery; a stator 12 disposed in the casing 4; a rotor 8 rotatably supported in the stator 12; a fan 11 which is disposed facing the vent hole in the casing 4, integrally rotated with the rotor 8, and has a body and blades provided at the body; and protrusions 2c, 3c which are disposed at positions facing tip parts 11a of the blades of the fan 11 and formed at positions located adjacent to an outer periphery of the vent hole of the casing 4.SELECTED DRAWING: Figure 1
