The present invention is an environment-friendly inner tube The inner tube is formed by a constituent including a Thermoplastic Elastomer TPE that efficiently improves toughness and oxidation resistance. When the inner tube is penetrated by a sharp article, its gas retaining property postposes air leakage and stiffens the inner tube, thus prolonging service life of the tire. The inner tube is fabricated by an injection molding machine with improved productivity. Thermoplastic Elastomer will not produce toxic substances, and overflow and wastes generated from manufacturing process can be recycled, thus avoiding waste of resources, saving the materials and lowering manufacturing costs with better industrial efficiency.