PROBLEM TO BE SOLVED: To provide an aseptic joining device capable of certainly fusion-cutting and joining two tubes when fusion-cutting and joining the tubes.SOLUTION: This aseptic joining device includes: an interlock pin 60 as a fixing member fixing a closed clamp lid part 3 such that the clamp lid part 3 is not opened by abutting on the clamp lid part 3, and bringing the clamp lid part 3 into a state that the clamp lid part 3 can be opened by releasing the abutment on the clamp lid part 3 a wafer WF as a heating member for heating and fusion-cutting a first tube T1 and a second tube T2 a heater 110 heating the wafer WF a temperature sensor 87 measuring the temperature of environment wherein a casing is placed and a control part 100 changing a time for which a current is carried through the heater 110 based on the temperature of the environment measured by the temperature sensor 87, and changing a time for which the wafer WF heats the first tube T1 and the second tube T2.
