Abstract: A cooling device for rocket engine nozzle comprising a first member including a cylindrical or tapered inner circumstance shape, channels provided over the part or all of the inner circumstance surface, and a helical groove part on each channel, and a second member including an outer circumstance surface of being the substantially same shape as the inner circumferential surface of the first member, and a nozzle-shaped cavity part therein to form a nozzle part, and then by assembling both of the members, forming tube parts corresponding to the shape of the helical groove parts as helical cooling channels placed on positions spaced predetermined distances from a throat part of the nozzle part, by which preventing coolant running in the helical cooling channels from excessively heated and helping the coolant perform its designed cooling ability to suppress nozzle erosion, upon flue gas of the rocket engine passing through the throat part.