The present invention relates to a structure of a rotor for a brushless motor which can improve structural stiffness, restrict noise generation by reducing vibration during the rotation, use cheap materials, reduce a fabrication cost by fabricating a back yoke and a base plate unit in a single body. improve durability, and efficiently cool a heat generated in the motor during the operation by facilitating an external air inflow. The structure of the rotor for the brushless motor includes: a steel plate frame provided with a base plate unit in a disc shape having a plurality of insertion holes at its center portion, a plurality of radiation holes being formed at a circumferential portion of the insertion holes, a plurality of blades being formed at side portions of the radiation holes by cutting: a back yoke unit curved and extended in the upward direction, having a predetermined height at the circumferential portion of the base plate unit; and a radius-direction enhancing unit formed at the upper end portion of the back yoke unit; one or a plurality of ring type permanent magnets fixedly connected to the inner side portion of the back yoke unit; a connecting member inserted into the insertion hole positioned at the center, and connected to the steel plate frame; and a fixing unit fixing a driving shaft inserted into the connecting member and connected to the other constitutional elements.