The PMSM is widely used in industry. In order to detect faults and to monitor the system, it is important to detect changes in load for systems in which the PMSM is installed.However, the price of sensors is high and it is difficult to install sensors because of space limitations. Therefore, a method is proposed to detect the load using the speed of the motor in a system without sensors. An FOC method for operating the motor and a detection method using speed fluctuation have been studied; however, the speed includes many error components such as motor inertia and measurement error. To improve the accuracy of the speed measurement, the pulse count method has been studied and implemented. Actual experiments were performed to verify the proposed algorithm. The proposed algorithm detects the load variation at approximately the same time as the actual load is applied.