The total internal reflection microscope has an illumination optical system that relays light from a light source with a relay optical system, forms an image of the light source on the incident pupil plane of the objective lens and irradiates a sample with the illumination light via an objective lens, has an angle adjustment mirror for changing the position of the image of the light source in a direction orthogonal to the optical axis, an optical detector for detecting the intensity of the returning illumination light reflected by the sample and collected by the objective lens, and a controller for determining the operation amount of the angle adjustment mirror, wherein the controller determines the operation amount of the angle adjustment mirror so that the illumination light is totally reflected at the sample based on the change in intensity of the returning light when the angle adjustment mirror is changed.