A scanning microscope includes a collecting lens that takes in a detection light, a focal position adjustment unit that moves in an optical axis direction of the collecting lens to make the collecting lens move in the optical axis direction, a detector positioned at a location that is optically conjugate to a pupil of the collecting lens, and a relay optical system that relays the pupil to the detector. The relay optical system includes a first optical element with a positive power, the first optical element being positioned in the focal position adjustment unit and converting the detection light that was converted by the collecting lens into a parallel light flux, into a convergent light flux to be emitted outside of the focal position adjustment unit, and a second optical element that is positioned outside of the focal position adjustment unit and between the detector and the first optical element.