A shape measuring method for measuring a surface shape of a measurement target includes dividing light from a light source into measurement light and reference light, the measurement light being obliquely incident upon a surface of the measurement target, the reference light being incident upon a reference mirror, introducing the measurement light reflected by the measurement target and the reference light reflected by the reference mirror to a photoelectric conversion element, detecting interference light formed by the measurement light and the reference light by the photoelectric conversion element while moving the measurement target, and measuring the surface shape of the measurement target based on an interference signal obtained from the measurement light that has been reflected at the same position on the surface of the measurement target.