A method of detecting a disconnection state of a power cable (10, 200, 300) in an inverter system, the method comprising: detecting a disconnection state of a first power cable by using a difference value between a battery voltage and a DC voltage supplied to an inverter through the first power cable; detecting a disconnection state of a second power cable by using a driving speed, a phase current instruction value, and an actual phase current value of a motor; and stopping driving of the motor if one of the first and second power cables is detected as being disconnected, wherein the detecting of the disconnection state of the second power cable comprises: checking a driving speed of the motor; determining if the checked driving speed of the motor exceeds a reference speed; determining if a phase current instruction value to drive the motor is greater than a first reference value if the driving speed of the motor exceeds the reference speed; determining if an actual phase current applied to the motor is less than a second reference value if the phase current instruction value is greater than the first reference value; and detecting the second power cable as being disconnected if the actual phase current is less than the second reference value, wherein the step of stopping driving of the motor comprises turning off a main relay if the actual phase current is less than the second reference value wherein the first reference value is set 50% of a theoretical current instruction value corresponding to a torque instruction; and wherein the second reference is set to a value greater than zero. detecting a disconnection state of a first power cable by using a difference value between a battery voltage and a DC voltage supplied to an inverter through the first power cable; detecting a disconnection state of a second power cable by using a driving speed, a phase current instruction value, and an actual phase current value of a motor; and stopping driving of the motor if one of the first and second power cables is detected as being disconnected, wherein the detecting of the disconnection state of the second power cable comprises: checking a driving speed of the motor; determining if the checked driving speed of the motor exceeds a reference speed; determining if a phase current instruction value to drive the motor is greater than a first reference value if the driving speed of the motor exceeds the reference speed; determining if an actual phase current applied to the motor is less than a second reference value if the phase current instruction value is greater than the first reference value; and detecting the second power cable as being disconnected if the actual phase current is less than the second reference value, wherein the step of stopping driving of the motor comprises turning off a main relay if the actual phase current is less than the second reference value wherein the first reference value is set 50% of a theoretical current instruction value corresponding to a torque instruction; and wherein the second reference is set to a value greater than zero. checking a driving speed of the motor; determining if the checked driving speed of the motor exceeds a reference speed; determining if a phase current instruction value to drive the motor is greater than a first reference value if the driving speed of the motor exceeds the reference speed; determining if an actual phase current applied to the motor is less than a second reference value if the phase current instruction value is greater than the first reference value; and detecting the second power cable as being disconnected if the actual phase current is less than the second reference value, wherein the step of stopping driving of the motor comprises turning off a main relay if the actual phase current is less than the second reference value wherein the first reference value is set 50% of a theoretical current instruction value corresponding to a torque instruction; and wherein the second reference is set to a value greater than zero.