An object of the invention is to provide a method and an apparatus for recycling plastics which is improved with respect to operation efficiency, operation environment, lowering degradation of plastics, recycling cost and environment load including saving energy. The recycling is made as follows: coarse-crushing used-up plastic products, separating plastic materials from other foreign matters by air blow separation, fine-crushing the separated plastics, washing the fine-crushed plastics by the process using a circulation flow including a spiral flow in which interaction between crushed plastics helps themselves clean without washing agents, dewatering the washed plastics, drying them, removing metallic matters by using metal detector, then feeding them directly without pelletizing to an injection molding machine of which nozzle part is equipped with filter and flow-switching mechanism for cleaning the filter by backwash reverse filtration.