Regarding predetermined positioning criteria (M.sub.1, M.sub.2),
((G.sub.1, G.sub.2), (N.sub.1, or N.sub.2), (K.sub.1, K.sub.2)), there is
provided image processing means (40B) for obtaining by image processing,
measured values (C.sub.D1, C.sub.D2) ((G.sub.D1, G.sub.D2), (N.sub.D1, or
N.sub.D2), (K.sub.D1, K.sub.D2)) and reference values (C.sub.R1,
C.sub.R2) ((G.sub.R1, G.sub.R2), (N.sub.R1, or N.sub.R2), (K.sub.R1,
K.sub.R2)), and for moving a work (W) in a manner that the measured
values (C.sub.D1, C.sub.D2) ((G.sub.D1, G.sub.D2), (N.sub.D1, or
N.sub.D2), (K.sub.D1, K.sub.D2)) and the reference values (C.sub.R1,
C.sub.R2) ((G.sub.R1, G.sub.R2), (N.sub.R1, or N.sub.R2), (K.sub.R1,
K.sub.R2)) coincide with each other, thereby positioning the work (W) at
a predetermined position.
