A total internal reflection illumination apparatus applied to a microscope which illuminates a sample through an objective having a numerical aperture enabling total internal reflection illumination, comprises a first total internal reflection mirror which is arranged in the vicinity of an outermost peripheral part of an observation optical path of the microscope to reflect an incident illumination light in a direction of the objective, a second total internal reflection mirror which is arranged at a symmetrical position with the first total internal reflection mirror to sandwich an observation optical axis and reflects return light reflected on a surface of the sample in a direction different from the illumination optical path, and a return light dimming part configured to dim the return light reflected by the second total internal reflection mirror.