Abstract: An ultra-thin spindle motor having a groove formed on the outer circumferential surface of a thrust bearing is disclosed. The present invention relates to an ultra-thin spindle motor among small-sized motor using a hydro dynamic pressure generating bearing and its object is to provide a spindle motor capable of stably driving without requiring a sleeve that was required to support a shaft in a radial direction in which a thrust bearing sleeve for coupling a hub and a thrust bearing is constructed and a radial hydro dynamic pressure generating groove is formed on the outer circumferential surface to thereby allow a radial hydro dynamic pressure to be generated and support a thrust bearing sleeve coupled integrally to the hub.