Abstract: A roof apparatus for a convertible car is provided, which includes a front roof and a rear roof which are folded and unfolded by a motor, a support provided at a lower portion of the rear roof for supporting the rear roof; wherein the support including, a base provided at a lower surface of the rear roof in a relatively rotatable manner; an output gear provided on the base that is motor driven; a driving gear engaged with the output gear to rotate on the base, a plurality of links rotatably engaged to the driving gear, and a latch connected to the respective links and rotated by the links on the base so as to be latched to or unlatched from the rear roof. The roofs folded and unfolded by the motor system are able to quickly operate and be accurately controlled. The unfolded roofs are firmly supported by the roof support for supporting the rear roof to increase the overall strength of the roof device.