Total internal reflection microscope

A total internal reflection microscope comprising an illumination optical system for relaying light from a light source with a relay optical system and forming an image of the light source on the incident pupil of an objective lens or the vicinity thereof and irradiating an observation object with the light through the objective lens, the total internal reflection microscope further comprising:

• an incident angle adjustment device for changing the position of the image of the light source in a direction orthogonal to a direction of the optical axis,
• an optical detector for detecting intensity of the returning light that is the light reflected by the observation object and collected by the objective lens, and
• a controller for determining the operation amount of the incident angle adjustment device, wherein
• the controller determines the operation amount of the incident angle adjustment device based on the change in intensity of the returning light detected by the optical detector when the incident angle adjustment device is operated.