A control circuit for a power converter apparatus comprising a power factor correction circuit including an inductor and operating in a current critical mode, the control circuit comprising: a first detector circuit (5, 21) that is configured to detect a current of the inductor, a current corresponding to the current of the inductor, or a current including the current of the inductor, to amplify a voltage corresponding to a detected current with a predetermined gain, and thereafter, to output an amplified voltage as a detected voltage; a comparator that is configured to compare the detected voltage with a predetermined second reference voltage, and to output a comparison result signal; a second detector circuit that is configured to detect an input voltage of the power converter apparatus; and a third detector circuit that is configured to detect an output voltage of the power converter apparatus, wherein the control circuit is configured to calculate a first reference voltage for preventing a detection delay and accurately detect a zero point of the inductor current by making a delay when detecting a zero value of the current of the inductor be substantially zero, the first reference voltage being based on the detected input voltage, the detected output voltage, a preset delay time, an inductance value of the inductor, a conversion coefficient used when converting the current detected by the first detector circuit (5, 21) into a voltage, a power supply voltage, and the gain, characterized in that the control circuit is configured to calculate the second reference voltage in consideration of a negative current required through the inductor for soft switching of the power converter apparatus by lowering the first reference voltage in an elliptical shape only for a predetermined time period, wherein the control circuit is configured to calculate the negative current necessary for the soft switching based on the input voltage detected by the second detector circuit, the output voltage detected by the third detector circuit, and an inductance of the inductor, and wherein the control circuit is further configured to calculate the second reference voltage by adding a voltage corresponding to the negative current, to the first reference voltage, and to output the second reference voltage to the comparator. a first detector circuit (5, 21) that is configured to detect a current of the inductor, a current corresponding to the current of the inductor, or a current including the current of the inductor, to amplify a voltage corresponding to a detected current with a predetermined gain, and thereafter, to output an amplified voltage as a detected voltage; a comparator that is configured to compare the detected voltage with a predetermined second reference voltage, and to output a comparison result signal; a second detector circuit that is configured to detect an input voltage of the power converter apparatus; and a third detector circuit that is configured to detect an output voltage of the power converter apparatus, wherein the control circuit is configured to calculate a first reference voltage for preventing a detection delay and accurately detect a zero point of the inductor current by making a delay when detecting a zero value of the current of the inductor be substantially zero, the first reference voltage being based on the detected input voltage, the detected output voltage, a preset delay time, an inductance value of the inductor, a conversion coefficient used when converting the current detected by the first detector circuit (5, 21) into a voltage, a power supply voltage, and the gain, characterized in that the control circuit is configured to calculate the second reference voltage in consideration of a negative current required through the inductor for soft switching of the power converter apparatus by lowering the first reference voltage in an elliptical shape only for a predetermined time period, wherein the control circuit is configured to calculate the negative current necessary for the soft switching based on the input voltage detected by the second detector circuit, the output voltage detected by the third detector circuit, and an inductance of the inductor, and wherein the control circuit is further configured to calculate the second reference voltage by adding a voltage corresponding to the negative current, to the first reference voltage, and to output the second reference voltage to the comparator.