PROBLEM TO BE SOLVED: To provide a non-cutoff flow passage closing device capable of attaining an easy insertion of a closing bag to be inserted into a pipe flow passage as well as its prevention of damage under a non-cutoff flow state and capable of positively closing the pipe flow passage.SOLUTION: This invention relates to a non-cutoff flow passage closing device in which an insertion guide cylinder 22 internally fitted and stored in a closing case 20 under a state where a closing bag 4 is shrunk can be moved within the closing case 20 and a branch pipe part B along an axis core Y of the branch pipe part B until at least a part of the extremity end of the insertion guide cylinder 22 becomes an abutting attitude where it abuts against an outer surface side circumferential edge 2a of a branch port 2 at an outer circumferential surface 1a of a fluid pipe 1, and a shaft core adjustment part 50 that can be slid and contacted with the inner surface of the insertion guide cylinder 22 is positioned at a location c
