A power transmission system for a vehicle is provided, including: a housing that can reserve oil therein; and a rotational member rotatably supported within the housing, with a surface of the rotational member being partly contactable with a surface of the oil reserved in the housing, in which the surface of the rotational member partly contactable with the oil surface includes a non-contact surface that is not in contact with any power transmission members, the non-contact surface having an oil repellent section. When the surface of the rotational member contacts the oil surface, the oil repellent section repels the oil quickly. Therefore, the amount of oil, which adheres to and rotates with the rotational member agitating the oil, decreases. This reduces oil heat generation and rotational resistance to the rotational member.