present embodiment the balloon catheter duct 10 includes a urethral catheter tube 13 provided with a first urethral catheterization passage 14 and a branch tube 11 provided with a first passage 12 when the user uses the indwelling urethral balloon catheter urine passes through the first urethral catheterization passage 14 also when a balloon of the balloon catheter 50 inflates or deflates a fluid such as sterile water or air flows through the first passage 12 a reservoir connection port 17 for use to connect a reservoir adapted to store sterile water or air is formed at one end of the branch tube 11 a urine drainage port 18 is formed at one end of the urethral catheter tube 13 the urine drainage port 18 can be connected for example with a cap for indwelling medical instrument disclosed in japanese patent laid open no 9 206370 a funnel portion 15 is formed at other ends of the branch tube 11 and urethral catheter tube 13 the funnel portion 15 is a substantially cylindrical member extending from the branch tube 11 and urethral catheter tube 13 the funnel portion 15 forms a space in which the first urethral catheterization passage 14 and first.