To provide an emergency detachment mechanism for a fluid handling device that has exceptional heat insulation performance and enables liquid hydrogen or another very-low-temperature fluid to be handled. An emergency detachment mechanism for a fluid handling device provided with a pair of couplers 1, wherein each of the pair of couplers 1 has a coupler body part 5 including an internal tube part 2 in which a fluid passes through an interior and which opens at a distal end side, an external tube part 3 which forms a vacuum layer 9 with the internal tube part 2 and which opens at a distal end side, and a connecting flange part 4 that closes off a space between the internal tube part 2 and the external tube part 3, a wall thickness of the connecting flange part 4 being less than a wall thickness of the external tube part 3.