A rotor for a motor, the rotor comprising: a plurality of rotor cores; a plurality of magnets magnetized such that magnetic flux is formed in a circumferential direction, the magnets and the rotor cores being alternately arranged in the circumferential direction; a coupler connected to a shaft; and a rotor frame comprising a coupler base connected to the coupler, an extension base extending from the coupler base in a radial direction, and a rotary base extending from the extension base in an axial direction of the shaft for supporting the rotor cores and the magnets while surrounding the rotor cores and the magnets, wherein the coupler base, the extension base, and the rotary base are integrally formed by injection molding, and the rotor frame is coupled to the coupler, the rotor cores, and the magnets, wherein the extension base is provided with crossing ribs that cross in the radial direction, the crossing ribs comprise one crossing rib extending obliquely and another crossing rib extending obliquely such that the crossing ribs cross each other and create a crossing point, and the extension base is further provided with a plurality of radial ribs that extend in the radial direction and are arranged in the circumferential direction at uniform intervals, wherein a first radial rib of the radial ribs extends through the crossing point in the radial direction, and a second radial rib of the radial ribs is connected to the circumferential opposite tips of the crossing ribs, so that the crossing ribs are provided between second radial ribs formed at circumferentially opposed sides of the first radial ribs, and so that six sections (S1, S2, S3, S4; S5, S6) are formed about the crossing point, wherein the extension base comprises a crossing zone formed between radial inner tips of the crossing ribs and radial outer tips of the crossing ribs, and a non-crossing zone located outside the crossing zone in the radial direction and connected to the rotary base, wherein the crossing zone and the non-crossing zone are partitioned by circumferential ribs formed in the circumferential direction, and wherein a vertical through part is formed between each of the crossing ribs and a corresponding one of the radial ribs to provide a passage through which air flows. a plurality of rotor cores; a plurality of magnets magnetized such that magnetic flux is formed in a circumferential direction, the magnets and the rotor cores being alternately arranged in the circumferential direction; a coupler connected to a shaft; and a rotor frame comprising a coupler base connected to the coupler, an extension base extending from the coupler base in a radial direction, and a rotary base extending from the extension base in an axial direction of the shaft for supporting the rotor cores and the magnets while surrounding the rotor cores and the magnets, wherein the coupler base, the extension base, and the rotary base are integrally formed by injection molding, and the rotor frame is coupled to the coupler, the rotor cores, and the magnets, wherein the extension base is provided with crossing ribs that cross in the radial direction, the crossing ribs comprise one crossing rib extending obliquely and another crossing rib extending obliquely such that the crossing ribs cross each other and create a crossing point, and the extension base is further provided with a plurality of radial ribs that extend in the radial direction and are arranged in the circumferential direction at uniform intervals, wherein a first radial rib of the radial ribs extends through the crossing point in the radial direction, and a second radial rib of the radial ribs is connected to the circumferential opposite tips of the crossing ribs, so that the crossing ribs are provided between second radial ribs formed at circumferentially opposed sides of the first radial ribs, and so that six sections (S1, S2, S3, S4; S5, S6) are formed about the crossing point, wherein the extension base comprises a crossing zone formed between radial inner tips of the crossing ribs and radial outer tips of the crossing ribs, and a non-crossing zone located outside the crossing zone in the radial direction and connected to the rotary base, wherein the crossing zone and the non-crossing zone are partitioned by circumferential ribs formed in the circumferential direction, and wherein a vertical through part is formed between each of the crossing ribs and a corresponding one of the radial ribs to provide a passage through which air flows.