A connection device for connecting a tubular connector to equipment comprises: a connection end fitting formed by a tubular body and a head mounted thereon, the head being provided with an opening leading into the tubular body and comprising a retaining groove; a flexible lock, which has an annular shape and is intended to be partially received in the retaining groove, the lock being provided with lugs extending radially toward the center of the lock, wherein the flexible lock is deformable and the lugs can close on the tubular connector and abut against the collar when the tubular connector is introduced into the connection end fitting; an unlocking ring having a collar for insertion into the connection end fitting, the collar including unlocking elements for interacting with the flexible lock to force the opening thereof when the unlocking ring is rotated.