PURPOSE: To improve assembling workability by providing a movement mechanism for moving a cam member back and forth and switching the other part to the state where it can be brought into contact with an inclined portion of the cam member or the state where it can not be brought into contact.

CONSTITUTION: The other part 20 is separated from one part 10 to return it to the original position and a band state body is transferred in the longitudinal direction, and a cam member 60 is moved to the advance position by a movement mechanism 50. When the other part 20 is moved toward the one part 10 again, the other part 20 is brought into contact with an inclined member 61 of the cam member 60, while the other part 20 is moved along the longitudinal direction with a fine pitch. Thus, a new one part 10 is brought to correspond to an empty engagement hole 22 which has not been engaged with the one part 10.