The utility model discloses an automatic balancer of wheels. The automatic balancer is characterized by being provided with two ring-shaped hollow tubular balance rings (2), wherein each balance ring is internally provided with dozens of grams of heavy mass metal powder hermetically and made from materials for making wheel hubs, and the two balance rings are respectively welded or fixed by a fastener (2.1) at the inner and outer periphery of the wheel hub (1). The heavy mass metal powder hermetically filled in each balance ring is 10-100 grams. The heavy mass metal powder is iron, lead, copper or zinc powder. The automatic balancer of wheels is applicable to adjusting the dynamic balance state of wheels, novel and ingenious in structure and especially obvious in the effect of adjusting the dynamic balance of wheels.