Insulation Resistance Measurement Apparatus and Method Thereof

An insulation resistance measurement apparatus includes a first resistance unit having one end connected to an anode of a battery and the other end connected to ground, and variably having a first resistance value or a second resistance value greater than the first resistance; a second resistance unit having one end connected to a cathode of the battery and the other end connected to ground, and variably having a third resistance value or a fourth resistance value greater than the third resistance value according to control; a voltage measurement unit configured to measure a voltage across the first or second resistance unit; and an insulation resistance calculation unit configured to calculate a first insulation resistance value between the anode of the battery and ground and a second insulation resistance value between the cathode of the battery and ground by using the first to fourth resistance values and the measured voltage.