To provide a balancer housing for an engine capable of surely reducing the noise of the engine by achieving the sufficient supporting rigidity of a crank shaft, while avoiding demerits such as the increase of the manufacturing cost and the increase of a weight of the engine caused by the complexity of a constitution.

A housing main body 12 of the balancer housing 11 is mounted in a state of being offset to a right side with respect to the crank shaft 4, a right side of the housing main body 12 is fastened to a right side of a cylinder block 2, a left side of the housing main body 12 is fastened to each bearing cap 5, and a left side of a baffle plate 13 extended left from the housing main body 12 is fastened to a left side of the cylinder block 2.