A lumbar support for a car seat includes a support element formed of a plate spring having a high elasticity to be positioned between traverse fixing bars which are mounted at upper and lower parts in a seat back for supporting a lumbar portion of a driver, and having a plurality of support wings formed at both sides and folded outwardly for surrounding the lumbar portion of the driver and a curved protrusion optionally formed in the center for supporting the lumbar portion of the driver, coupling units for coupling the support plate with the traverse fixing bars, a supporting height control element for steplessly controlling a protruded height of the support plate which is selectively and curvedly protruded at a side of the support plate, and a pelvic supporting element formed at a lower part of the support plate and connected to the support plate to contact and support hips of the driver, wherein the contact between the seat and the driver may be improved by forming the pelvic supporting element at the lower part of the support plate for stably supporting the lumber region and the pelvic region of the driver seating in the seat, so that it is possible to promote the safety driving by preventing the driver from being tired easily even in case of the long time driving, and to prevent the bad pose of the driver by the stable supporting of the lumbar region and the pelvic region of the driver, thereby maintaining the safety and the health of the driver.