Recently, measures to address environmental problems and resource problems have been strongly desired. Consequently, the energy saving of machine tools has been promoted at production sites. Thus, the efficiencies of motors and coolants have been improved for the energy saving of machine tools. However, replacing machines and peripherals is time-consuming and expensive. Therefore, we focused on the power consumption by the feed drive system and spindle of a machine tool during machining. Considering of the energy conservation in the feed drive system and spindle is practical and effective to existing machine tools. In this study, we propose the simulator that calculates the energy consumption of the feed drive system and spindle using the NC program. It is possible to calculate the energy consumption without actual machining and measuring. Using the simulation result, we can change the tool path and machining conditions, leading to a reduction in machining power consumption. This study devised a method for calculating the power consumption of the feed drive system using the NC program using only the reference power consumption of the machine tool. Then, the measured and simulated power consumptions for machining were compared to verify the validity of the proposed method.