Fluorescent image obtainment method and apparatus, fluorescence endoscope, and excitation-light unit

A fluorescent image obtainment apparatus includes a light illumination means (130, 150) that illuminates a region to be observed with illumination-light and excitation-light at the same time, and an imaging means (110) that captures an image composed of light reflected from the region illuminated with the illumination-light and an image composed of fluorescence output from the region illuminated with the excitation-light. Further, the apparatus includes an image processing means (170) that produces an ordinary image based on the image of the reflection light and a fluorescent image based on the image of fluorescence, and a light amount control means (186) that controls the light amount of the illumination-light so that a representative luminance value of the ordinary image becomes a predetermined luminance value and the light amount of the excitation-light so that the ratio of the light amount of the excitation-light to that of the illumination-light becomes a predetermined ratio.