A sample shape measuring method includes a step of preparing illumination light passing through a predetermined illumination region, a step of applying the illumination light to a sample, and a predetermined processing step. The predetermined illumination region is set so as not to include the optical axis at a pupil position of the illumination optical system and is set such that the illumination light is applied to part of the inside of the pupil and the outside of the pupil at a pupil position of the observation optical system. The predetermined processing step includes a step of receiving light, a step of obtaining the quantity of light, a step of calculating the difference or the ratio between the quantity of light and a reference quantity of light, and a step of calculating the amount of tilt in the surface of the sample from the difference or the ratio.