To provide a fixture in which the elastic deformation of a spacer with respect to a reference insertion load of the fixture to a fixture mounting hole of a body can be enlarged in comparison with conventional spacers, and a CSA fixing device.

A fixture 1 comprises: a clip body 10; a lock pin 50; and a spacer 70. The spacer 70 includes an elastic deformation part 76 which is formed from a spacer portion closer to a spacer center of a leg part fitting hole 72 than both ends of the leg part fitting hole 72 in one direction of the spacer to both ends and capable of being deformed in a clip body axial direction. The spacer 70 has a rectangular shape in a planar view, and the one direction of the spacer 70 is e.g., a length direction of the spacer 70. Thus, the elastic deformation of the spacer 70 is increased. In a CSA fixing device 2 employing the fixture 1, the spacer 70 elastically deforms the elastic deformation part 76 to remove backlash among a main body head part 12, a tab 80b, the spacer 70 and a body 90 regardless of variation in distance between the main body head part 12 and the body 90.