An internal combustion engine includes a crankshaft, a variable flow rate oil pump apparatus including oil pumps having a drive shaft thereof operatively connected with the crankshaft, and a rod-shaped oil passage switching valve operatively connected with the oil pumps. The oil passage switching valve and the drive shaft of the oil pumps are arranged such that axial directions thereof are parallel to an axial direction of the crankshaft. Also, the oil pumps and the oil passage switching valve are disposed so as to overlap each other in the axial direction of the crankshaft. With such configuration of the engine, the effect on various components around the pump can be reduced, while downsizing the oil pump and the engine.