A method and a device for bending a metal hollow thick walled member to a predetermined angle without deviation of the bending center position and without separation from a half die when presser die moves up. With a pair of guide plates (GP1 and GP2) turnably attached to a center pin CP kept horizontal and the axis center of the center pin intersecting with the axis center of the metal hollow thick walled member PM, the member PM is mounted on a half die (82a). When die holding members (80a and 80b) fixedly connected to the above guide plates and kept horizontal are inclined and separated from each other as the center pin lowers, the member PM is bent to the predetermined angle and held on the half die (82b). When the center pin that can be moved vertically by a guide member moves down to a predetermined position, a contact portion (96b) contacts the inclined surface of a stopper (92b) to allow a base plate (16) to receive a pressing force from an upper die via the stopper.