A balancer apparatus of an engine includes a crank case, a crankshaft supported by the crank case and including a crank web having a pin connecting portion connected with a crank pin and a counter weight portion, a balancer shaft arranged in parallel with the crankshaft and rotated in cooperation with the crankshaft and a balance weight provided on the balancer shaft and rotated integrally with the balancer shaft. The balancer shaft is installed at a position of overlapping the crank web when viewed from an axial direction of the crankshaft.