Abstract: A method of holding a curved circuit board in a flat fashion and a wire bonding apparatus thereof, including suction cavities provided in a suction stage to which a curved circuit board is suctioned. While evacuating air from the vacuum suction cavities, a capillary attached to the tip end of a bonding arm is lowered to press a part of the curved circuit board down thus having at least one of the vacuum suction cavities sealed by the circuit board, allowing the remaining vacuum suction cavities to be sealed successively so that the curved circuit board is straightened to be flat and suction-held on the suction stage. The vacuum suction cavities are sealed with by straightened circuit board, and the circuit board is held on the suction stage in place.