An emergency detachment mechanism for a fluid handling device, the emergency detachment mechanism provided with a pair of couplers ,wherein each of the pair of couplers has a coupler body part including an internal tube part in which a fluid passes through an interior and which opens at a distal end side, an external tube part which forms a vacuum layer with the internal tube part and which opens at a distal end side, and a connecting flange part that closes off a space between the internal tube part and the external tube part, a wall thickness of the connecting flange part being less than a wall thickness of the external tube part, opening parts for allowing a fluid to circulate between the pair of couplers are formed in each of the distal end sides of the coupler body parts, each of the pair of couplers has an emergency shutoff valve including a valve seat that sections off the opening part and a valve body that opens and closes the opening part, the valve bodies each include a valve body base part accommodated in the coupler body part and a valve body distal end part covering a distal end side of the valve body base part, the valve bodies are urged toward the distal end sides of the coupler body parts, the opening parts are closed off due to the valve body base parts being engaged by pressure contact with the valve seats when the pair of couplers are in a detached state of being separated from each other, seals for keeping the coupler body parts liquid-tight are disposed between the valve seats and the valve body base parts, and during the detached state, only the valve body distal end parts, a portion of each of the valve seats, and the coupler body parts face the exterior. each of the pair of couplers has a coupler body part including an internal tube part in which a fluid passes through an interior and which opens at a distal end side, an external tube part which forms a vacuum layer with the internal tube part and which opens at a distal end side, and a connecting flange part that closes off a space between the internal tube part and the external tube part, a wall thickness of the connecting flange part being less than a wall thickness of the external tube part, opening parts for allowing a fluid to circulate between the pair of couplers are formed in each of the distal end sides of the coupler body parts, each of the pair of couplers has an emergency shutoff valve including a valve seat that sections off the opening part and a valve body that opens and closes the opening part, the valve bodies each include a valve body base part accommodated in the coupler body part and a valve body distal end part covering a distal end side of the valve body base part, the valve bodies are urged toward the distal end sides of the coupler body parts, the opening parts are closed off due to the valve body base parts being engaged by pressure contact with the valve seats when the pair of couplers are in a detached state of being separated from each other, seals for keeping the coupler body parts liquid-tight are disposed between the valve seats and the valve body base parts, and during the detached state, only the valve body distal end parts, a portion of each of the valve seats, and the coupler body parts face the exterior. <EOS>