PURPOSE: To detect two kinds of fluorescence of specific wavelength without performing mechanical switching by a rotary filter, etc.

CONSTITUTION: The endoscope 4 of this fluorescence observing endoscope device 1 comprises a light guide 10 which introduces a laser beam emitted from a laser 9 to a living body inner cavity, a concave lens 11 which diffuses and illuminates the laser beam, an objective lens 12 which projects the fluorescent image of a lesion 3 on a color image pickup element 5 and an optical filter 13 which transmits specific wavelength of the fluorescent image. The optical filter 13 is provided with transmission characteristic to transmit a green color of 500-540nm and a red color of 640-700nm.