PURPOSE: To improve the inspection efficiency of an inspection device by carrying container materials one by one along a guide line and separately housing acceptable and nonacceptable materials after discriminating the materials by comparing the patterns read from the materials by means of the inspection device with a reference pattern written in a buffer memory.

CONSTITUTION: Since a pinch roller 2 is obliquely fitted against a guide side plate 11, a container material 1 put between the roller 2 and a drive roller 3 is properly advanced by means of the roller 2 along the plate 11. When the material 1 passes below a camera 31 at a fixed speed, a fiber sensor 63 detects the leading edge section of the material 1 and, after the leading edge section is detected, a linear image sensor connected to the camera 31 successively reads the prints on the material 1 and compares the read prints with a reference pattern. When both signal coincide, the material is discriminated as acceptable and sent to a housing section 37 through a sorting and discharging section D. Non-acceptable materials 1 are housed in another housing section 38 through the section D. Therefore, the efficiency is improved and differences between individuals resulted from manual operations can be eliminated.