PURPOSE: An AC(Alternating Current) generator for vehicle is provided to improve the durability by blocking oil within an engine room and foreign materials flowing into a brush room of a generator. CONSTITUTION: A rotatory shaft(140) is installed within a bracket(110) in order to be linked with a rotor. A slip ring(170) is provided with a supporting shaft(171) on an external side of the rotatory shaft(140). A brush holder(180) is provided with a sliding guide(185) separately installed on an outside thereof in order to wrap the slip ring(170) and provided with a brush room(182) therein being opposite to the slip ring(170). A brush(181) is inserted into the brush room(182) to be stacked to the slip ring(170). A sealing unit(200) is provided on an end of the sliding guide(185).
