The present invention relates to a motor structure, which has a shaft tube and a stator set disposed on a base. The shaft tube is in form of a circular tube, the bottom side thereof is in an integrally-formed and closed pattern, and an abrasive gasket, a limit member and a bearing are disposed in the shaft tube, such that a spindle of a rotor can be inserted in the bearing and rotate therein. As the limit member has an annular wall with a specific height, a plurality of limit protrusions extended inward from the inner wall of the through hole can snap a reduced neck of the spindle to limit its axial displacement, thereby attaining the design object of reserving enough space for accommodating an end section of the spindle, reducing necessary parts, assembling process, and saving production cost.