A device and method for controlling the changing operation of an on-load tap changer (LTC) that interrupts current passing the current zero point of a commercial frequency are provided. The device may include a current zero point detecting unit that detects a zero point in the waveform of current passed through the LTC, a current zero point cycle measuring unit that measures the cycle of the current zero point detected by the current zero point detecting unit, a commercial frequency determining unit that generates an output signal when the cycle of the current zero point measured by the current zero point cycle measuring unit corresponds to a commercial frequency, and an actuation signal output unit that outputs an actuation signal used to have the LTC carry out tap changing operation in response to the output signal of the commercial frequency cycle determining unit.