Abstract: A supporting structure for a rotor comprises two holding members, a supporting member, and a fixing member that is fixed in place. Each holding member comprises a hole and an inner flange formed on an inner periphery defining the hole. The supporting member comprises a supporting portion and the fixing member has a hole. An end of a shaft of a rotor extends through the holes of the fixing members with an end face of the shaft resting on the supporting portion of the supporting member. A retainer is engaged in a retaining groove of the shaft to thereby retain the shaft in place. The shaft and the inner flanges of the holding members have a minimum gap or a slight contact therebetween.