The reference position is determined, by using a test piece, for optically detecting the orientation of a component such as a chip for use in placement apparatus such as a chip mounter. Light is emitted from a light source toward a light sensor to cast a shadow of the test piece onto the light sensor. A first position of an end of the shadow when the pick-up device rotates at a first angle, a second position of the other end of the shadow when the pick-up device rotates at a second angle, and a third position of either end of the shadow when the pick-up device rotates at a predetermined third angle, are detected on the light sensor. Accordingly, the positional relationship of the light source, the light sensor, and the pick-up device is determined as a reference position, based on the positional data.