1. A three-dimensional shape measurement apparatus that measures a coordinate of a surface of a target object based on a captured image including the target object onto which a pattern is projected, comprising: a projection unit configured to project a first pattern and a second pattern onto a measurement area in which the target object is placed and a reference marker is arranged, wherein the first pattern is a pattern for obtaining a coordinate of a surface of the target object and the second pattern is a pattern for correcting a projection position by the projection unit; an image capturing unit configured to capture an image of the measurement area onto which at least one of the first pattern and the second pattern are projected; and a control unit, including at least one processor, configured to: derive, based on an image captured by the image capturing unit, a first correction value for correcting a position of the projection unit and the image capturing unit, and a second correction value for correcting projection position of the projection unit; and obtain a coordinate on a surface of the target object based on an image captured by the image capturing unit, and the first correction value and the second correction value that have been derived, wherein the projection unit and the image capturing unit are fixed on a support structure and the position of the projection unit and the image capturing unit is changed by fluctuation of the support structure.