In a flame detector having an optical head, a plurality of light- taking optical fibers are arranged so as to provide different directions of fields of vision at their front ends. Therefore, the watching regions of burner flame has been widened, and even if the primary combustion zone moves back and forth with respect to the tip of the burner due to the change in load, the flame can be accurately detected providing high reliability. Junction optical fibers and wiring optical fibers are separately provided in addition to the light-taking optical fibers. Therefore, when one or more optical fibers are damaged, only the damaged optical fibers are required to be replaced with new ones providing cost reduction in maintenance. Two or more photosensitive elements having different sensitive wavelength regions are used. Therefore, various types of flames having various wavelengths can be effectively detected providing wider detection range when compared with conventional apparatus.
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