Abstract: An oil pump apparatus may include a housing provided with at least one hydraulic line formed therein, a power source assembled to the housing and configured to apply torque through a drive shaft, and two pumps disposed respectively at both end portions of the housing concentrically with the drive shaft, operably connected to each other through a torque delivery shaft, and pumping oil by receiving the torque from the drive shaft, wherein an inner rotor of one pump may be operably connected to the drive shaft, integrally formed with a boss portion, and operably connected to the torque delivery shaft operably connected to an inner rotor of the other pump through the boss portion.