This three-dimensional measurement device includes: a light source, a lens guiding light from the light source to a subject, a photomask disposed on the optical axis between the light source and lens and having a predetermined pattern, a driving device changing the position of one member from the lens and photomask or changing an optical characteristic of the lens, and a control unit controlling the driving device. The control unit fixes an image formation position for light/dark pattern light formed by the photomask at the position of the subject by fixing the position of said member or the optical characteristic of the lens when specifying a first mode, and varies the position of the member or the optical characteristic of the lens to vary the image formation position for the light/dark pattern light such that the light/dark difference caused by the light/dark pattern light is smaller than in the first mode when specifying a second mode.