A sample shape measuring apparatus includes a light source unit, an illumination optical system, a detection optical system, a light detection element, and a processing apparatus. A scanning unit relatively moves a light spot and the sample. Illumination light applied to the sample is transmitted through the sample, and light transmitted through the sample is incident on the detection optical system. The light detection element receives light. The illumination optical system or the detection optical system includes an optical member. The processing apparatus obtains a quantity of light based on a received light, calculates at least one of a difference and a ratio between the quantity of light and a reference quantity of light, calculates an amount of tilt at a surface of the sample, and calculates a shape of the sample from the amount of tilt.