PROBLEM TO BE SOLVED: To provide an aseptic joining device capable of preventing that a cassette having stored heating plate members is erroneously taken out from inside a casing when fusion-cutting and joining tubes.SOLUTION: This aseptic joining device 1 includes: a casing 2 fixing a first tube T1 and a second tube T2 and a cassette storage unit 84 which is disposed in the casing 2 and stores, inside the casing 2, a cassette WC storing wafers WF as heating plate members for fusion-cutting the first tube T1 and the second tube T2. The cassette storage unit 84 has: a getting-out prevention projection member 140 projecting into the cassette storage unit 84 to prevent that the cassette WC gets out of inside the cassette storage unit 84 and a cassette take-out prevention device 82 holding a state that the getting-out prevention projection member 140 has projected into the cassette storage unit 84 to prevent that the cassette WC is taken out.
