A power control apparatus for an image forming apparatus, comprising: an AC input voltage detection unit for detecting an AC input voltage from an AC power supply, said AC input voltage detection unit being turned off or on by a relay; a reception unit sequentially receiving inputs of voltage values corresponding to AC input voltages from the AC power supply when the relay of the AC input voltage detection unit is turned on; a power control table storage unit storing a power control table in which a power control parameter corresponding to the AC power supply voltage is matched with each group of the voltage values corresponding to the same AC power supply voltage, wherein a group of the voltage values is defined by a plurality of voltage values; a decision unit determining to which group the received voltage values belong among the plurality of groups, whenever the reception unit receives the input of the voltage value and deciding the group, to which a predetermined number of voltage values belongs among the plurality of voltage values sequentially received by the reception unit, among the plurality of groups using the determination result; and a power control unit controlling power supply according to the power control parameter matched with the decided group; characterized in that: in the power control table, an identification value of the AC power supply voltage is further matched with a group, said identification value being a predetermined value which corresponds to an AC power supply voltage of a country; the power control apparatus further comprises a conversion unit converting the received voltage value into the matched identification value, whenever the reception unit receives the input of the voltage value; the decision unit determines whether a current identification value agrees with a previous identification value whenever the conversion unit performs the conversion, and decides the identification value when agreements are continuously produced by a predetermined number or when the number of agreement reaches a predetermined number; the power control unit controls the power supply according to the power control parameter matched with the decided identification value; and when the number of disagreements reaches a predetermined number, the decision unit decides an identification value indicating a maximum voltage among the current identification values in the disagreement. an AC input voltage detection unit for detecting an AC input voltage from an AC power supply, said AC input voltage detection unit being turned off or on by a relay; a reception unit sequentially receiving inputs of voltage values corresponding to AC input voltages from the AC power supply when the relay of the AC input voltage detection unit is turned on; a power control table storage unit storing a power control table in which a power control parameter corresponding to the AC power supply voltage is matched with each group of the voltage values corresponding to the same AC power supply voltage, wherein a group of the voltage values is defined by a plurality of voltage values; a decision unit determining to which group the received voltage values belong among the plurality of groups, whenever the reception unit receives the input of the voltage value and deciding the group, to which a predetermined number of voltage values belongs among the plurality of voltage values sequentially received by the reception unit, among the plurality of groups using the determination result; and in the power control table, an identification value of the AC power supply voltage is further matched with a group, said identification value being a predetermined value which corresponds to an AC power supply voltage of a country; the power control apparatus further comprises a conversion unit converting the received voltage value into the matched identification value, whenever the reception unit receives the input of the voltage value; the decision unit determines whether a current identification value agrees with a previous identification value whenever the conversion unit performs the conversion, and decides the identification value when agreements are continuously produced by a predetermined number or when the number of agreement reaches a predetermined number; the power control unit controls the power supply according to the power control parameter matched with the decided identification value; and when the number of disagreements reaches a predetermined number, the decision unit decides an identification value indicating a maximum voltage among the current identification values in the disagreement.