A method for supporting a printed board. Includes a first step of conveying to a specified position by a conveying a printed board having a first reference hole and a second reference hole device a for setting a position and posture thereof. A second step stops the conveyed printed board at the specified position with a stop member. A third step inserts a first reference pin provided at the specified position into the first reference hole of the stopped printed board. A fourth step inserts a second reference pin into the second reference hole of the printed board. The second reference pin is movable in parallel to a mounting surface of the printed board and in any arbitrary direction relative to the first reference pin. A fifth step pinches the printed board to hold the position and posture thereof of a holding device with the first reference pin and the second reference pin both inserted. A sixth step draws out, after the fifth step, at least one reference pin of the first reference pin and the second reference pin from its corresponding reference hole. A seventh step mounts after the sixth step, an electronic component onto the printed board under the control of a control unit.