A balancer device (15) for an engine (100) includes a housing (20), a pair of balancer shafts (40, 50) rotatably supported by means of at least a bearing member (26, 27) provided in the housing, a pair of balancer weights (43, 53) each balancer weight eccentrically provided at an outer circumferential surface of each balancer shaft, and a pair of gears (41, 51) each gear provided at each balancer shaft. The housing is formed with a through hole (20b) at a side wall (20a) thereof, each balancer shaft is provided with each balancer weight at an end thereof, the balancer weight being placed at a through hole side relative to the bearing member which supports the balancer shaft, and an end portion (42a) of the balancer shaft extends into the through hole along the axis of the balancer shaft to restrict a fluid communicating therethrough.