Seat swivel device for vehicle

A seat swivel device for a seat, the seat swivel device comprising:

• a support plate;
• a first fixing plate mounted on an upper surface of the support plate;
• a second fixing plate stacked on and assembled with an inner peripheral end of the first fixing plate;
• a third fixing plate stacked on and assembled with an outer peripheral end of the second fixing plate;
• a retainer housing a plurality of balls that are rollably stored;
• and
• a swivel rail comprising a mounting plate, the mounting plate including an inner slide end and an outer slide end, the inner slide end formed on an inner side of the mounting plate and disposed between the first fixing plate and the second fixing plate so as to be slidably supported by inner balls of the retainer, and the outer slide end formed on an outer side of the mounting plate and disposed between the first fixing plate and the third fixing plate so as to be slidably supported by outer balls of the retainer;
• wherein the first fixing plate, the second fixing plate, the third fixing plate, the retainer and the swivel rail are annular-shaped,
• wherein the inner balls are positioned radially inward relative to the protruding portion, and the outer balls are positioned radially outward relative to the protruding portion, and
• wherein a load applied on the seat is configured to be transferred to the raised portion of the mounting plate and to be supported by the inner balls and the outer balls.