In order to automate the positioning at the steps of reference position
teaching and normal manufacturing at respective ports at the start-up of
an equipment in a semiconductor manufacturing equipment equipped with a
positioning device and a carrying robot and enhance productivity, 2
points W.sub.1 and W.sub.2 at which the circumference of a disc-like
object 47 such as a wafer and the locus 43 of a detection means cross are
detected, and the center position A of a disc-like object is calculated
using the specific point O on the perpendicular bisector 42 of the
section of a line combining 2 points with these and the radius r of the
disc-like object, in the present invention. Thereby, the carrying robot
could carry out the positioning work and not only the correction of a
carrying route but also the reference position teaching at the start-up
of equipment could be automated using the result. When there is a notched
portion, the circumference of a disc-like object is detected by 2 loci of
the detection means and a correct center position is detected. Further, a
mix manufacturing using wafers with different diameters can be also
carried out by detecting the circumferences of dislike objects with an
unknown radius by the 3 loci of the detection means and determining the
radius.