This paper describes position estimation method for interior permanent magnet synchronous motor (IPMSM) using idea of pattern matching technique. High frequency signal injection methods are conventional method of sensorless vector control for IPMSM in standstill and very low speed region. Those methods are used when the value of phase inductance can be assumed to be a sinusoidal function of rotor position. Generally, automobile motors are designed to have high torque density. In such motors, the value of phase inductance would be complicated because of the magnetic saturation, which negatively affects the accuracy of rotor position estimation. To solve those problems, we have proposed in this paper a new approach for sensorless vector control of the IPMSM with heavy magnetic saturation. This approach, utilizes pattern matching. Experimental results are included to demonstrate the applicability of proposed methods.