A three-dimensional measurement apparatus for calculating three-dimensional shape information of a target object, comprising: capturing means for capturing reflected pattern light of stripe pattern light formed by alternately arranging a bright portion and a dark portion as first image data, and capturing reflected pattern light of reversed stripe pattern light formed by reversing the bright portion and the dark portion of the stripe pattern light as second image data; determination means for determining a boundary position between the bright portion and the dark portion based on the first image data and the second image data; and reliability calculation means for calculating a reliability indicating accuracy of the boundary position from a correlation between a first luminance gradient of the first image data and a second luminance gradient of the second image data.