PURPOSE: To reduce cost and to enhance efficiency by forming a plastic preform and molding the same in a perfect plastic receptacle produced from a predetermined amt. of a material without generating scrap.

CONSTITUTION: The plastic sheet supplied to an extruder 3 is cut into a precut plastic form 1 or a preform by an on-line press 2. In this case, formed scrap is again introduced into the extruder 3 from a grinding machine 5 by a pneumatic conveyor 5'. Thereafter, the scrap can be transported to remote positions 12, 12 by a truck 10. The precut form 1 is heated therein by a heater 6 and a product 14 is produced by a mold 7 and a counter mold 8. Therefore, it is unnecessary to place a thermoforming machine at the same position 11 as the extruder and an eccentric press and the transport cost of a precut disc becomes extremely low. The product is thermoformed at a position near to a market and the distribution thereof is accelerated.