An apparatus for measuring an insulation resistance, comprising: a first insulation resistance measurement unit connectable to a cathode terminal of a battery; a second insulation resistance measurement unit connectable to an anode terminal of the battery, wherein the second insulation resistance measurement unit further includes a direct current power applying unit; a first switch and a second switch to form different first and second circuits, the first circuit being formed by connecting the first insulation resistance measurement unit to the cathode terminal through the first switch, and the second circuit being formed by connecting the second insulation resistance measurement unit to the anode terminal through the second switch; a voltage detection unit configured to sense a first insulation detection voltage (V 1) and a second insulation detection voltage (V 2) applied to the first insulation resistance measurement unit and the second insulation resistance measurement unit respectively; a control unit configured to calculate a cathode terminal-side insulation resistance value (R Leak(+)) and an anode terminal-side insulation resistance value (R Leak(-)) from the first insulation detection voltage and the second insulation detection voltage and circuit equations derived from the first circuit and the second circuit; characterized in that the control unit is configured to calculate the cathode terminal-side insulation resistance value and the anode terminal-side insulation resistance value using the following Equation: R L e a k + = V B a t − A V B a t − C − A C D V B a t − A + B C R L e a k − = V B a t − A V B a t − C − A C B V B a t − A + A D ∴ A = V 1 R 2 R 1 + V 1 ∴ B = V 1 R 2 ∴ C = V D C − V 2 R 2 R 1 − V 2 ∴ D = V D C − V 2 R 2 in which V Bat denotes a battery voltage value, V 1 denotes the first insulation detection voltage, V 2 denotes the second insulation detection voltage, V DC denotes a voltage value of the direct current power applying unit, R 1 denotes a first resistance value, R 2 denotes a second resistance value, R Leak(+) denotes the cathode terminal-side insulation resistance value, and R Leak(-) denotes the anode terminal-side insulation resistance value. a first insulation resistance measurement unit connectable to a cathode terminal of a battery; a second insulation resistance measurement unit connectable to an anode terminal of the battery, wherein the second insulation resistance measurement unit further includes a direct current power applying unit; a first switch and a second switch to form different first and second circuits, the first circuit being formed by connecting the first insulation resistance measurement unit to the cathode terminal through the first switch, and the second circuit being formed by connecting the second insulation resistance measurement unit to the anode terminal through the second switch; a voltage detection unit configured to sense a first insulation detection voltage (V 1) and a second insulation detection voltage (V 2) applied to the first insulation resistance measurement unit and the second insulation resistance measurement unit respectively; a control unit configured to calculate a cathode terminal-side insulation resistance value (R Leak(+)) and an anode terminal-side insulation resistance value (R Leak(-)) from the first insulation detection voltage and the second insulation detection voltage and circuit equations derived from the first circuit and the second circuit; characterized in that the control unit is configured to calculate the cathode terminal-side insulation resistance value and the anode terminal-side insulation resistance value using the following Equation: R L e a k + = V B a t − A V B a t − C − A C D V B a t − A + B C R L e a k − = V B a t − A V B a t − C − A C B V B a t − A + A D ∴ A = V 1 R 2 R 1 + V 1 ∴ B = V 1 R 2 ∴ C = V D C − V 2 R 2 R 1 − V 2 ∴ D = V D C − V 2 R 2 in which V Bat denotes a battery voltage value, V 1 denotes the first insulation detection voltage, V 2 denotes the second insulation detection voltage, V DC denotes a voltage value of the direct current power applying unit, R 1 denotes a first resistance value, R 2 denotes a second resistance value, R Leak(+) denotes the cathode terminal-side insulation resistance value, and R Leak(-) denotes the anode terminal-side insulation resistance value.