An inspecting apparatus for detecting a foreign matter in a container
having a recessed and protruding shape includes: illumination units
arranged annularly on inner and outer sides of an annular carrier line
and casting parallel lights onto the inspection subject from the outside
thereof; image pickup units arranged on the outside of the annular
carrier line and receiving lights from the inspection subject,
simultaneously from two directions around the inspection subject, and
picking up images of the inspection subject; wherein the image pickup
units pick up images of the inspection subject in a state where an angle
.theta.1 formed by light-receiving axes of the image pickup units is 30
to 90 degrees and an angle .theta.2 formed by the light-receiving axis of
the image pickup unit and the light of the illumination unit next to the
image pickup unit is 30 to 60 degrees.