A disposable cartridge (22, 150, 200) capable of being detachably installed in an opening of a casing of a puncture device or blood component measuring device, comprising: a housing (70, 152, 204) insertable into an opening of the puncture device or the measuring device; a displacement member (72, 158, 208) displaceable along axial directions of the housing (70, 152, 204); and a flexible member (80, 162, 210) being tiltable with respect to a side surface of the housing (70, 152, 204) and provided on the housing (70, 152, 204) wherein the tiltable flexible member (80, 162, 210) has one end supported by the housing (70, 152, 204) and another end capable of facing an opening of the puncture device or the blood component measuring device, and the flexible member (80, 162, 210) is tilted by the displacement member (72, 158, 208) upon displacement thereof, wherein the displacement member (72, 158, 208) has an engaging portion (96, 166, 216) for engaging the other end (88, 168, 214) of the flexible member (80, 162, 210), and wherein before the housing (70, 152, 204) is installed in the puncture device or the blood component measuring device, the other end of the flexible member (80, 162, 210) is engaged by the engaging portion (96, 166, 216); wherein the displacement member (72, 158, 208) is disposed so as to be capable of abuting against a step disposed in the opening of the puncture device or the blood component measuring device, and when the housing (70, 152, 204) is installed into the puncture device or the blood component measuring device through an opening thereof, the displacement member (72, 158, 208) is displaced along the axial directions with respect to the housing (70, 152, 204) to release the displacement member (72, 158, 208) from the engagement with the flexible member (80, 162, 210); and wherein the flexible member when released from the engagement is disposed as to be capable of abuting against the casing thereby of preventing the cartridge (22, 150, 200) from being reinstalled in a puncture device or blood component measuring device; characterized in that the displacement member (72, 158, 208) is mounted on the housing (70, 152, 204), and when the housing (70, 152, 204) is installed in a puncture device or blood component measuring device, the flexible member (80, 162, 210) is disengaged from the engaging portion (96, 166, 216) and tilted. a housing (70, 152, 204) insertable into an opening of the puncture device or the measuring device; a displacement member (72, 158, 208) displaceable along axial directions of the housing (70, 152, 204); and a flexible member (80, 162, 210) being tiltable with respect to a side surface of the housing (70, 152, 204) and provided on the housing (70, 152, 204) wherein the tiltable flexible member (80, 162, 210) has one end supported by the housing (70, 152, 204) and another end capable of facing an opening of the puncture device or the blood component measuring device, and the flexible member (80, 162, 210) is tilted by the displacement member (72, 158, 208) upon displacement thereof, wherein the displacement member (72, 158, 208) has an engaging portion (96, 166, 216) for engaging the other end (88, 168, 214) of the flexible member (80, 162, 210), and wherein before the housing (70, 152, 204) is installed in the puncture device or the blood component measuring device, the other end of the flexible member (80, 162, 210) is engaged by the engaging portion (96, 166, 216); wherein the displacement member (72, 158, 208) is disposed so as to be capable of abuting against a step disposed in the opening of the puncture device or the blood component measuring device, and when the housing (70, 152, 204) is installed into the puncture device or the blood component measuring device through an opening thereof, the displacement member (72, 158, 208) is displaced along the axial directions with respect to the housing (70, 152, 204) to release the displacement member (72, 158, 208) from the engagement with the flexible member (80, 162, 210); and wherein the flexible member when released from the engagement is disposed as to be capable of abuting against the casing thereby of preventing the cartridge (22, 150, 200) from being reinstalled in a puncture device or blood component measuring device; characterized in that the displacement member (72, 158, 208) is mounted on the housing (70, 152, 204), and when the housing (70, 152, 204) is installed in a puncture device or blood component measuring device, the flexible member (80, 162, 210) is disengaged from the engaging portion (96, 166, 216) and tilted.