PURPOSE: To securely detect a specific color pattern even when the background is dark by performing the color separation of reflected light from a body to be detected, which includes a color pattern, through plural filters, performing photoelectric conversion and outputting a specific color signal, and thus detecting the specific color pattern.

CONSTITUTION: A photoelectric conversion part 23 obtains three output signals, and color difference detecting circuits 25 and 26 output two signals by the output difference between two photoelectric converters. Further, a hue detecting circuit 31 outputs the output of a slicing circuit 28 through an AND circuit 29. Firstly; when bits 0W2 of a shift register 32 are set to 1 by a signal which corresponds to a bar mark 31, an AND circuit 33 generates an output. Similarly, when bits 27W29, 14W16, and 0W2 of the shift register 32 are set to 1 by signals which correspond to marks 31, 32, and 33, AND circuits 35, 34, and 33 generate outputs respectively, and an AND circuit 36 also generates an output, thus outputting a pattern detection signal.