Provided is a syringe holder (13) for holding a syringe (11) provided with a threaded engagement section with which an administration part for administering a medical solution to a living organism is engaged through threads. The syringe holder (13) is provided with: a cylinder body (41)； a holder opening (41a)； an engagement claw (43) with which one surface of the flange (24) of the syringe is engaged； an engagement protrusion (51) with which the other surface of the flange (24) of the syringe is engaged； a deformation promotion section (42) for promoting the deformation of the engagement claw (43) toward the outside radially of the cylinder body (41)； a pivoting restriction section (44) coming into contact with the small-diameter section (24b) of the flange (24) of the syringe to restrict the circumferential pivoting of the syringe (11) relative to the cylinder body (41)； and a radial movement restriction section (45) coming into contact with the large-diameter section (24a) of the syringe to restrict the radial movement of the syringe (11) relative to the cylinder body (41).
