An apparatus for measuring an insulation resistance according to the present invention includes: a first distribution resistor connected to a positive terminal of a battery and a ground; a first switch connected to the positive terminal of the battery and the first distribution resistor; a second distribution resistor connected to a negative terminal of the battery and the ground; a second switch connected to the negative terminal the battery and the second distribution resistor; and an insulation resistance measurement unit measuring a resistance value of a negative electrode insulation resistor of the battery using a first voltage applied to the first distribution resistor and measuring a resistance value of a positive electrode insulation resistor of the battery using a second voltage applied to the second distribution resistor.