PROBLEM TO BE SOLVED: To provide an index unit capable of easily and stably acquiring an image for use in calibration without using a fluorescent paint in a scanning confocal endoscope system, and an image acquisition method.SOLUTION: The index unit for use in image evaluation of the scanning confocal endoscope system comprising a scanning confocal endoscope for applying excitation light to a subject and receiving fluorescent light excited by the excitation light, and a processor for generating an image on the basis of the fluorescent light that the scanning confocal endoscope receives, includes: an LED capable of emitting light with a wavelength equivalent to that of the fluorescent light a collimating lens attached to a light-emitting plane of the LED and a chart attached to the collimating lens and including an index for image evaluation formed thereon. The light from the LED passes through the collimating lens to be applied to the chart such that the index emits light, or a part of the chart, other than the index, emits light.SELECTED DRAWING: Figure 4
