Abstract: In a parts mounting apparatus, suction nozzles are mounted on a rotating carrier driven by a motor. With rotation of the rotating carrier, parts are sucked by the nozzles at a feed station and carried to a mounting station where the parts such as electronic parts are mounted on substrates, for example. A counter counts output pulses from an encoder mounted in the motor driving the rotating carrier. A microcomputer determines the rotational speed and rotational position of the rotating carrier from the count value of the counter. Based on the result of the determination, the microcomputer calculates a timing for delivering a signal for switching the nozzles between two different pneumatic states.