PURPOSE: To obtain a part mounting device capable of applying flux and the like.

CONSTITUTION: A screen mask 45 is fixed to the one end face of a cylinder 42, a piston rod 43 is made to protrude from the other end face of the cylinder 42, a dummy nozzle 41 whose tip is fixed to the piston rod 43 is mounted on a mounting head in a detachable manner, a nozzle holding pad tentatively holding the dummy nozzle and a suction nozzle is disposed in a movable range of the mounting head, and viscous fluid L is filled into the cylinder 42 and pushed towards the screen mask 45 by the piston rod 43. By a previously inputted mounting program, a suction nozzle is replaced with a dummy nozzle when viscous fluid is applied onto a prescribed spot of a board, a mounting head is moved, the end face of a cylinder on a screen mask side is brought into contact with the prescribed spot of the board, and furthermore the mounting head is moved towards the board at a prescribed speed by a certain distance to relatively move a piston rod to the cylinder.