The present invention provides a drainage tube introducer wherein while a drainage tube is fitted over an introducing end portion (42) protruding through a pin hole (32) and is introduced through an incision portion (4) into an infected portion (2) in cooperation with the introducing end portion (42), a stop block (52) is pressed by pushing a sleeve (70) frontward, which bends an operating lever (50) made of an elastic material to release the stop block (52) from a stop hole (38). Accordingly, a pin (40) is moved rearward by an elastic member (60) to withdraw the introducing end portion (42) protruding through the pin hole and to separate the drainage tube introduced into the infected portion (2) from the introducing end portion (42).