PURPOSE: To make it possible to find accurately the correction amount of the mounting position of a component on the basis of detection of the projection of the component using an optical detection means in the case where the component, which is clamped by the suction nozzle of a surface mounter, is a cylindrical component.

CONSTITUTION: A cylindrical component is held by a suction nozzle and thereafter, detection of the projection of the component using a laser unit is conducted in a state that the nozzle is set at a first angle of rotation to measure the position of the center of the projection of the component, then, detection of the projection of the component using the laser unit is conducted in a state that the nozzle is rotated by 90° and is set at a second angle of rotation to measure the position of the center of the projection of the component and the correction amounts in the X direction and the Y direction of the mounting position of the component are found on the basis of the distance between the position of the center of the projection of the component at each angle of rotation and the position of the component to correspond to the center of the nozzle.