A three-dimensional shape measuring method includes: projecting a first grid pattern based on a first light and a second grid pattern based on a second light onto a target object in such a way that the first grid pattern and the second grid pattern intersect each other, the first light and the second light being lights of two colors included in three primary colors of light; picking up, by a three-color camera, an image of the first grid pattern and the second grid pattern projected on the target object, and acquiring a first picked-up image based on the first light and a second picked-up image based on the second light; and performing a phase analysis of a grid image with respect to at least one of the first picked-up image and the second picked-up image and calculating height information of the target object.