To stably separate a socket from a plug without being affected by pressure of fluid flowing in an inner passage and to apply to ultrahigh pressure fluid.

The structure of the emergency release coupling is provided with a locking pin 40 arranged between a socket main body 13 of the socket 12 and a valve cylinder 25 of the plug 19 for applying a resistance force between the time when connections by a connecting pin 33, a second connecting member 34, and a third connecting member 37 are all released and the socket 12 and the plug 19 start to separate to the time when the socket 12 and the plug 19 are completely separated. Thereby, the locking pin 40 is able to generate a resistance force between the socket 12 and the plug 19 that separate with great force by pressure of hydrogen gas remaining in a space S defined between a socket side shutoff valve 18 and a plug side shutoff valve 24, and the force in the separating directions of the socket 12 and the plug 19 can be alleviated.