Recently, permanent magnet synchronous motor are applied to various applications such as electric vehicle, aerospace, medical service and military applications due to several outstanding characteristics. Because of the importance of high reliable operation in these areas, many research related to the fault detection and diagnosis of inverter system are conducted. In this paper, new simple fault detection method of voltage source inverter for permanent magnet synchronous motor is proposed. The feasibility of the proposed method are improved by simulation and experiment. By the simulation and experiments, rapid detection characteristic of the proposed method has been proved without any additional voltage sensor.