it is the object of this invention to provide a gas dynamic pressure bearing system with high rigidity and reliability . the unit is configured such that a thrust bearing sends lubricating gas under pressure in a radial direction , and a radial bearing sends the gas toward the thrust bearing , thereby increasing the bearing rigidity . in addition , one or more dynamic pressure generating grooves which constitute the thrust bearing are extended and connected to a particle catching holes formed in a shaft . with those configurations , the dust particles are trapped in the catching hole and are kept away from the bearing gaps .