A medical instrument is provided with: an illumination section radiating excitation light for exciting a fluorescent substance given to a subject, to the subject an image pickup section photoelectrically converting reflected light from the subject to which the excitation light is radiated, to pick up an image of the subject a reading section holding pixel signals obtained by the photoelectrical conversion and capable of reading the pixel signals non-destructively while changing amplification factors of the held pixel signals by a predetermined unit of pixels and an image processing section determining an arithmetic mean of the pixel signals read with different amplification factors by the reading section to generate an image. The medical instrument improves visibility of each fluorescent area without occurrence of position displacement even in the case where multiple fluorescent areas with a relatively large brightness/darkness difference exist within one screen.
