A ball joint is manufactured by molding a holder through casting by using a ball as a core and joining a shaft member to the ball after the casting through electric resistance welding. The ball joint includes: the ball; a resin sliding contact member including a first opening portion and a second opening portion that expose a spherical surface of the ball in opposite directions; the holder molded through the casting by using the ball and the resin sliding contact member as a core, the holder being obtained by integrally molding a closing portion that is held in contact with a part of the ball, which projects from the second opening portion of the resin sliding contact member; and the shaft member joined to another part of the ball, which is exposed from the first opening portion of the resin sliding contact member, through the electric resistance welding.