Spindle motor and driving device of recording disk having the same

In the present invention, disclosed is a spindle motor. The spindle motor includes a rotating member which has a protrusion unit protruding to form a gap narrower than a bearing gap; a protrusion corresponding unit protruding to face the protrusion unit; and a fixing member supporting the rotating member to rotate the rotating member. The protrusion unit includes a dynamic pressure thrust groove for generating the dynamic pressure of a thrust fluid in the protrusion unit. The protrusion unit has radial length shorter than the protrusion corresponding unit which has a flat surface facing the dynamic pressure thrust groove.