PURPOSE: To efficiently pick up a part having a strong magnetism and capable of neglecting the effect of a residual mangetism by providing a magnet vertically moved by a cylinder and a thin plate interposed between the part and magnet on a magnetic chuck used for an automatic assembly machine.

CONSTITUTION: A piston rod 10 of a machine part for reciprocating a magnet 8, that is, an air cylinder 9 are connected to the magnet 8 and a thin plate 12 is sticked to the base 11 where the air cylinder 9 is fixed. A part 1 is swung to the swing hole 3 of a swing plate 2. The magnet 8 is arranged above the part 1 through the thin plate 12 interposed between them. When this magnet 8 is pressed against the thin plate 12 by the machine part 9, the magnetic force of the magnet 8 acts on the part 1 by penetrating the thin plate 12, and thus the part 1 is closely fitted to the thin plate 12. The part 1 can be picked up from the swing hole 3 by moving the thin plate 12 upwards in this state.