Ball bearing

A ball bearing, comprising:

• an inner ring and an outer ring spaced apart from each other, each being rotatable;
• a cage part including a first cage and a second cage rotatably installed between the inner ring and the outer ring and having ball receiving parts formed along circumferential direction;
• balls disposed in the ball receiving parts and rotating with the cage part as at least one of the inner ring and the outer ring rotates;
• and
• magnets providing a magnetic force to the balls,
• wherein
• the first cage has first seating parts formed between the ball receiving parts and on which one side of the magnets is placed,
• the second cage has second seating parts connected to the first seating parts and on which the other side of the magnets is placed,
• each of the first cage and the second cage has contact parts spaced apart each other in circumferential direction, the contact parts of the first cage and the second cage contact each other, and the ball receiving parts are formed by the contact parts, the first cage and the second cage,
• the contact parts of the first cage and the second cage have screw holes through which screws are inserted to couple the first and second cages,
• magnet receiving parts are formed between the first and second seating parts, and
• the screw holes are in communication with the magnet receiving parts.