A fixture unit assuredly fits a fixed unit including a gap portion including a first wall surface and a second wall surface opposing each other. Provided are a fixture unit and a fixture apparatus including a fitting pin fitting a gap portion of a fixed unit, the gap portion including a first wall surface and a second wall surface opposing each other, where the fitting pin includes: a fixed pin inserted to the gap portion to contact the first wall surface; a moving pin inserted to the gap portion to be pressed on the second wall surface; and a base to which the fixed pin is fixed, and the moving pin includes a bottom portion in an arc form with a center being a central axis of movement, and the bottom portion fitting slidably with respect to a concave portion provided for the base.