To provide a balancer device which can reduce the number of assembling man-hours and improve the axial center accuracy of a bearing a balancer shaft.

The balancer device 10 includes: driving and driven balancer shafts 11, 21; a balancer housing 30 including a lower housing 31 and an upper housing 32; a pump housing 51 which is formed integrally with one end of the lower housing 31; and a pump cover 56 forming a pump chamber 63 in cooperation with the pump housing 51. One end of the side of the pump housing 51 of the driven balancer shaft 21 is inserted into the pump chamber 63 and connected to an inner rotor 61, one end of the driving balancer shaft 11 having a small sprocket 7 provided therein is protruded from the balancer housing 30, and both the balancer shafts 11, 21 are pivoted on only the balancer housing 30 and the pump housing 51.