Cycloid reducers have high reduction ratio, high efficiency, high stiffness and compact size so as to be an attractive candidate for limited space and precision application such as industrial robot. In case of the cycloid drive, the cycloid disk makes contact with a number of pin-rollers simultaneously and eccentric shafts transmit not only torque from the spur gear stage to the cycloid disk, but also torque from the cycloid disk to the output disk. Therefore, contact, bearing and structure should be considered together during analysis. This paper presents a finite element (FE) analysis of the torsional rigidity of a cycloid drive considering multi-contact. The bearing for the eccentric shaft is modeled as distributed springs around the shaft. FE analysis of an ideal rigid cycloid drive was performed and verified with theoretical calculations. The effects of structural stiffness of a disk, contact stiffness of pin-rollers, and bearing stiffness were investigated. Accurate contact forces acting on each pin-rollers and torsional rigidity of a cycloid drive system were evaluated simultaneously as the cycloid disk rotates.