In intraocular observation of the eye, the slit lamp microscope 1causes the illumination light emitted by the illumination system 8 to enter the inside of the eye via the head lens 20 and causes an intraocularly reflected light of this illumination light to enter the observation system 6 via the head lens 20 in a state that an illumination optical axis O2 and an observation axis O1 are arranged so as to be nonparallel and a head lens optical axis OF and the observation optical axis O1 are arranged so as to be separate right and left.