A washing machine having a ball balancer coupled to the drum to compensate for a dynamic imbalance during rotation of the drum, the ball balancer including a ring-shaped racer having a closed internal space in which a plurality of balls and viscous oil are accommodated, the ring-shaped racer including a first injection molded member and a second injection molded member joined to each other to form the closed internal space, the first injection molded member including a first side wall, a second side wall and a connecting wall between the first side wall and the second side wall, the first injection molded member having an open side opposite to the connecting wall, and the second injection molded member is adapted to cover the open side of the first injection molded member.