A positioning apparatus for positioning an object in respective axis directions of an X-axis, a Y-axis perpendicular to the X-axis, and a Z-axis orthogonal to the X-axis and the Y-axis and positioning the object around the Z-axis within a plane parallel to the X-axis and the Y-axis is provided. A fastener detachably fastens the retainer. A gap is formed between a first reference surface of the retainer and the second reference surface of the fastener when a fixing shaft of the retainer is inserted into a fixing hole of the fastener, an outer surface of a pyramid part of the fixing shaft fits to an inner surface of the fixing hole and the object is positioned in the X-axis direction and the Y-axis direction. The first reference surface and the second reference surface come into contact with each other when a fastening part of the fastener pulls the fixing shaft, the pyramid part or the fixing hole elastically deforms, and the fixing shaft is further pulled into the fixing hole with maintaining the fitting between the outer surface of the pyramid part and the inner surface of the fixing hole.