A system to recycle plastics, which enables a supply of recycled plastics having a stable quality required for the recycled products. A system to recycle a used plastic material as a resin material including (a) means to sort used plastic materials for the purpose of recycling said used plastic materials, (b) means to crush and melt said used plastic material after it has been sorted, (c) reviving means to regain a desired property, and (d) means to measure a physical property of a reclaimed plastic after it has been revived and to indicate said measured physical property for quality assurance.