To provide a thrust bearing of high reliability, whereby thrust wearing powder generated in a thrust slide surface is prevented from infiltrating in a dynamic pressure fluid bearing, and extending of a life of a motor can be attained.

In a dynamic pressure fluid bearing 2, a bearing side thrust washer 7 is provided, which has a protruded part 6 preventing thrust wearing powder from infiltrating in a radial bearing side. A rotary shaft side thrust washer 16, which is provided with a recessed pat 15 accumulating thrust wearing powder in a position opposing the protruded part 6 provided in the bearing side thrust washer 7, is pressed through a spring washer 14. By bringing a thrust slide surface 17 to the bearing side thrust washer 7 into contact by pressing force of the spring washer 14 when a rotary shaft is stopped, thrust wearing powder is prevented from dropping in a surface side of the rotary shaft, and extending of a life can be attained.