1. A three-dimensional measurement apparatus comprising a light irradiation unit adapted to irradiate a measurement target with pattern light, an image capturing unit adapted to capture an image of the measurement target irradiated with the pattern light by the light irradiation unit, and a measurement unit adapted to measure a three-dimensional shape of the measurement target from the image captured by the image capturing unit, the three-dimensional measurement apparatus further comprising: a change region extraction unit adapted to extract a change region where a change has occurred when comparing an image of the measurement target captured in advance by the image capturing unit with the image of the measurement target captured by the image capturing unit; and a light characteristic setting unit adapted to set characteristics of the pattern light to be emitted by the light irradiation unit from the change region extracted by the change region extraction unit, wherein the measurement unit measures the three-dimensional shape of the measurement target at the change region in an image captured by the image capturing unit after irradiation of the change region with the pattern light with the characteristics set by the light characteristic setting unit.