Panel integrating method

An outer panel and an inner panel are integrated by placing peripheral parts of the outer panel on a top surface of a lower mold such that bending parts formed by bending the peripheral parts of the outer panel are set up upward; placing a central portion of the outer panel on a top surface of a lifting device; lifting the central portion of the outer panel by the lifting device to open leading end sides of the bending parts of the outer panel outward; placing the inner panel on the top surface of the outer panel so as to superimpose those onto each other; lowering the central portion of the outer panel by the lifting device; and pressing the bending parts toward the lower mold by an upper mold to further bend the bending parts, and making the bending parts to closely contact with the peripheral parts of the inner panel.