A sealed compressor comprising: an electric component including a stator and a rotor; a compression component actuated by the electric component; a sealed container which accommodates the electric component and the compression component and stores lubricating oil therein; wherein the compression component includes a shaft including a main shaft section to which the rotor is fastened and an eccentric shaft section, a cylinder block having a compression chamber, a piston reciprocatable inside the compression chamber, a connecting member for coupling the piston to the eccentric shaft section, and a main bearing unit mounted to the cylinder block and supporting the main shaft section such that the main shaft section is rotatable, a thrust ball bearing mounted to a thrust surface of the main bearing unit; and the thrust ball bearing includes a plurality of balls held in a cage, an upper race having main surfaces one of which is in contact with upper portions of the balls; and a lower race having main surfaces one of which is in contact with lower portions of the balls; wherein raceway grooves (137, 138) formed by annular grooves are provided on the main surface of the upper race and the main surface of the lower race, respectively, the main surfaces facing each other; and wherein the balls are placed on the raceway groove of the upper race and the raceway groove of the lower race characterized in that the main bearing unit is provided on the thrust surface with a bearing extending section extending in an axial direction of the main shaft section, and the bearing extending section has an inner peripheral surface facing an outer peripheral surface of the main shaft section; wherein the cage and the lower race are disposed such that an inner peripheral surface of the cage and an inner peripheral surface of the lower race face an outer peripheral surface of the bearing extending section; and wherein a first clearance is formed between the outer peripheral surface of the main shaft section and an inner peripheral surface of the upper race, wherein the first clearance is smaller than a clearance formed between the outer peripheral surface of the bearing extending section and the inner peripheral surface of the cage, thereby constituting first limiting means limiting a radial displacement of the upper race with respect to the shaft. an electric component including a stator and a rotor; a compression component actuated by the electric component; a sealed container which accommodates the electric component and the compression component and stores lubricating oil therein; wherein the compression component includes a shaft including a main shaft section to which the rotor is fastened and an eccentric shaft section, a cylinder block having a compression chamber, a piston reciprocatable inside the compression chamber, a connecting member for coupling the piston to the eccentric shaft section, and a main bearing unit mounted to the cylinder block and supporting the main shaft section such that the main shaft section is rotatable, a thrust ball bearing mounted to a thrust surface of the main bearing unit; and the thrust ball bearing includes a plurality of balls held in a cage, an upper race having main surfaces one of which is in contact with upper portions of the balls; and a lower race having main surfaces one of which is in contact with lower portions of the balls; wherein raceway grooves (137, 138) formed by annular grooves are provided on the main surface of the upper race and the main surface of the lower race, respectively, the main surfaces facing each other; and wherein the balls are placed on the raceway groove of the upper race and the raceway groove of the lower race characterized in that the main bearing unit is provided on the thrust surface with a bearing extending section extending in an axial direction of the main shaft section, and the bearing extending section has an inner peripheral surface facing an outer peripheral surface of the main shaft section; wherein the cage and the lower race are disposed such that an inner peripheral surface of the cage and an inner peripheral surface of the lower race face an outer peripheral surface of the bearing extending section; and wherein a first clearance is formed between the outer peripheral surface of the main shaft section and an inner peripheral surface of the upper race, wherein the first clearance is smaller than a clearance formed between the outer peripheral surface of the bearing extending section and the inner peripheral surface of the cage, thereby constituting first limiting means limiting a radial displacement of the upper race with respect to the shaft.