Abstract: In an apparatus and a method for controlling operation of a reciprocating compressor which is capable of operating a compressor stably by detecting a phase difference and using an inflection point of the phase difference, an apparatus and a method for controlling operation of a reciprocating compressor including an electric circuit unit operating a reciprocating compressor by varying a stroke with motion of a piston, a phase difference detecting unit detecting a phase difference of a current and a voltage from the electric circuit unit, a phase inflection point detecting unit detecting a phase inflection point by being inputted the phase difference, and a stroke controlling unit being inputted the detected phase inflection point from the phase inflection point detecting unit and applying a voltage to the electric circuit unit in order to make the stroke correspond to the phase inflection point can control a TDC of a piston regardless of load variation, improve an operation efficiency of a reciprocating compre