A device mounting structure for mounting a load maintaining mechanism (20) on a hydraulic cylinder (10), a pipe (17) for suppling and discharging working oil to and from the hydraulic cylinder (10) being connected to the load maintaining mechanism (20) such that the working oil is led thereto, includes a single coupling portion (30) that includes a screw hole (32) and is provided on the hydraulic cylinder (10), and a bracket (40) to which the load maintaining mechanism (20) is fixed, the bracket (40) being coupled to the coupling portion (30) via a first screw member (50) that is screwed into the screw hole (32), wherein the bracket (40) includes a first through hole (43) through which the first screw member (50) is passed so as to leave a gap in a radial direction.