An object of the present invention is to provide a novel mandrel using a used mandrel, a method of use thereof and a production method thereof. The mandrel of the present invention has an inner layer formed from a thermoplastic resin composition containing an age resister and an outer layer made from a thermoplastic resin which covers the outer circumference of the inner layer. Preferably, the mandrel of the present invention is used for forming a rubber hose and preferably, the inner layer of the mandrel of the present invention is made from a thermoplastic composition obtained by pulverizing a used mandrel for forming a rubber hose.