To provide a fluorescence observation endoscope instrument which can display a fluorescence image based on excitation light having a plurality of wavelengths in one examination.

A laser unit 40 incorporates a plurality of semiconductor lasers 50-1, 50-2, and 50-3 having different oscillation wavelengths. A system control circuit 42 makes the laser unit 40 sequentially repeatedly emit laser light of different wavelengths from the semiconductor lasers 50. The emitted laser light irradiates a portion to be examined as excitation light through a light guide 16 and a light distribution lens 11. Fluorescence emitted from biotissue excited by the laser light is imaged on a color imaging element 13 by an object lens 12. Then, the excitation light emitted from the semiconductor lasers 50-1, 50-2 and 50-3 is cut off by an excitation light cutting off filter 14.