This specimen shape measurement method involves a step S10 for preparing an illumination light which passes through a prescribed illumination region, a step S20 for irradiating a specimen with the illumination light, and a prescribed treatment step S30. The prescribed illumination region is configured such that the optical axis is not contained in the pupil position of an illumination optical system, and is configured such that, in the pupil position of the observation optical system, the illumination light is illuminated onto a portion inside of the pupil and to outside of the pupil. The illumination light passes through the specimen, and the light emitted from the specimen is incident into the observation optical system. The prescribed treatment step S30 includes a step S31 for receiving light emitted from the observation optical system, a step S32 for calculating the intensity of the received light, a step S33 for calculating the difference between, or the ratio of, the light intensity and a reference ligh
