Abstract: An oil regulating pump for supplying oil to an engine, comprises: a pump housing provided with a suction route and a discharge route; a driving shaft inserted into said housing and rotated by the engine; a primary plunger rotated by the driving shaft; a secondary plunger inserted into a hole provided in an end of the primary plunger and formed a pump chamber communicable with the suction route and the discharge route for pumping; a motor provided with a mechanism for converting a rotation movement into a linear movement; a cam shaft abutted on an end of said driving shaft and linearly displaced by said motor, to reciprocate the driving shaft and to change a reciprocation stroke of the driving shaft; and a control device for controlling rotation of the motor.