When a mounting head is moved upward of a rear side conveyor across and over a front side conveyor after a component suction operation, it is determined whether or not there is a possibility that a component sucked by a suction nozzle may interfere with a component mounted on a circuit board on the front side conveyor. When so determined, a head lifting mechanism is caused to lift up the mounting head to a position where the component sucked by the suction nozzle does not interfere with the mounted component. Thereafter, the mounting head is moved upward of the rear side conveyor, and the head lifting mechanism is caused to lower down the mounting head to an initial height position. Thereafter, the component is mounted on a circuit board on the rear side conveyor.