Rotating and adjusting mechanism of seat for vehicle

An engaging and sliding portion (21) having a substantially inverted-U cross sectional shape is formed in a lower base (11). An upper base (13) is arranged via an engaging and sliding portion (21) of the lower base (11) and a first rolling member (23). A sliding portion (25) having a substantially U cross sectional shape and engaging with the engaging and sliding portion (21) is formed in a holding member (15). A second rolling member (27) is provided between the sliding portion (25) of the holder (15) and the engaging and sliding portion (21) of the lower base (11). A recess (13a) is formed at a position of an adhered portion of the holder (15) in the upper base (13). A position of an adhered portion in a seat main body is formed in a substantially linear shape. A mounting portion (15a) having a substantially inverted-U cross sectional shape is formed in the holder (15). A rotating lever (45) having a lock hook (45a) inserted to a lock hole (62) of the lower base (11) is pivoted to the upper base (13). Lever guides (43, 57) for guiding the lock hook (45a) are provided.