A medical guiding microtube in which at the tip of a synthetic resin tube a balloon having substantially the same outer diameter as said tube is attached and a ball-like body connecting at the tip of said tube through yarn in defined length is provided within the balloon having optionally a hole for leaking fluid, and it can be safely introduced to peripheral blood vessel and when used as leak balloon catheter it can control precisely and in good reproducibility a timing for leaking therapeutic liquid.
