The servo system of a surface permanent magnet synchronous motor is operated by current sensors to control the motor torque. However, a current sensor has often offset and gain deviation caused by age-related deterioration and thermal variation. These errors lead to d - q axis current ripple and torque ripple, degrading the performance of the servo system. In order to overcome these problems, a new estimation and compensation method for current measurement errors by using a current simulator is proposed. The method aims to decrease torque ripple caused by both offset and gain deviation during current measurement. Experimental results confirm that the proposed method satisfactorily suppresses current ripple and torque ripple caused by current measurement error.