1. A three-dimensional shape measurement apparatus that measures a three-dimensional shape of a target object, comprising: a projection unit configured to project a pattern image to a predetermined measurement area including a support structure on which the target object is placed, said projection unit being configured to project a coordinate calculation pattern image to the target object and project a marker pattern image to the support structure; an image capturing unit configured to capture an image of the predetermined measurement area; a derivation unit configured to derive, based on an image captured by said image capturing unit when said projection unit projects the marker pattern image to the support structure, a first correction value for correcting a position fluctuation of a support structure that fixes said projection unit and said image capturing unit, and a second correction value for correcting a fluctuation of a projection position by said projection unit; and a coordinate calculation unit configured to calculate a plurality of coordinates on a surface of the target object based on an image captured by said image capturing unit when said projection unit projects the coordinate calculation pattern image to the target object, and the first correction value and the second correction value that have been derived by said derivation unit.