With the spread of motors, magnetically geared motors are attracting attention. In this paper, the electromagnetic force that causes vibration in magnetically geared motor is examined. The characteristics of the electromagnetic force in a magnetically geared motor is investigated using a three-dimensional finite element method analysis. From the analysis results. It was confirmed that the fundamental excitation mode of the electromagnetic force reaches its maximum at five times the fundamental frequency. To verify the validity of the analytical results, measurements on a prototype were carried out. It was confirmed that the analysis result showed a good agreement with the measured values.