An instrument (20) for confirming the position of an indwelling gastrostomy catheter (10), and a method of confirming the indwelling position thereof, with which it is possible to reduce cleaning costs, and which does not cause any discomfort to a patient. An instrument for confirming the indwelling position of a gastrostomy catheter which is indwelling in a hole formed between the surface of the skin of the patient and the inner surface of the stomach wall comprising a fiberscope (23) and a protective cover. Furthermore, the tip end of the protective cover (24) comprises a light-transmissive window part (24a) and a wire (24c) that is linked to the outer periphery at the tip end of the protective cover.
