Balancer device has upper and lower housings 3 and 4 having therein an accommodation section 10, a pair of drive and driven side shafts 5 and 6 which are rotatably supported by four plain bearings 11 to 14 provided in the accommodation section and to which a rotation force is transmitted from a crankshaft, and arc band-shaped thrust receiving portions 32a and 33a which thrust flange portions of drive and driven gears 8 and 9 provided at the drive and driven side shafts respectively can contact from a thrust direction. First and second oil storing grooves 34 and 35, groove passages 36 and 37 and vertical groove passages 38a to 39b are formed at the thrust receiving portions on a gravity direction lower side with respect to a meshing portion of the both gears. With this configuration, it is possible to suppress occurrence of abrasion of the thrust receiving portion.