Having a crankshaft and two balancer shafts

摘要

A balancer shaft of an engine includes a pair of journal portions, a first stage balance weight and a second stage balance weight. The first stage balance weight is formed between the journal portions and eccentrically arranged with respect to an axis. The second stage balance weight is formed on a center part of the first stage balance weight in the axial direction and projects outward from the first stage balance weight in a radial direction. The balancer shaft has a recess portion on the opposite side of the eccentricity direction.