The push rod 31 is made of a flexible material such as nylon, silicone, polytetrafluoroethylene, polyacetal, ethylene tetrafluoride and the like in the form of a rod with a diameter equal to or slightly smaller than the inside diameter of the preparation-retaining member 30, and adjusted to be suitable for keeping the preparation 2 loaded in the preparation-retaining member 30 at a distal end ther