Abstract: A method of producing a hose having low permeability includes the steps of preparing a rubber mandrel having an outer releasing layer made of fluoride rubber, applying a silicon-based releasing agent having a viscosity of 300-1000 cs to the releasing layer in a state where the mandrel is being moved, and extruding a molten resin and coating it onto the releasing agent-applied mandrel while the mandrel is being moved, thereby forming a resin layer. By virtue of the provision of the releasing layer and also the application of the releasing agent to the releasing layer, the releasability of the mandrel is enhanced, thereby preventing the resin layer of the resultant hose from being injured when the mandrel removed therefrom. Hence, if the hose is used for transferring a refrigerant gas such as freon refrigerant, it is free from gas leakage, and shows high durability.