PURPOSE: To provide a method of separation of various constituents out of a compound plastic product without use of separation tank for slurry or liquid, and without use of air floating apparatus.

CONSTITUTION: Blocks of material to be disposed of consisting of plastic shell material and plastic foam material are crushed and broken with a rough crusher 20, separated with a cyclone unit 28, conveyed upward to a feeding hopper 36, and then sorted with a sorting screen 40. Separation apparatus is equipped with a feeding conveyer, a vertical lift. bucket conveyer, and an overhead feeding hopper. Two density fractions are formed on a table of a density separation fluidized bed. Heavier grain of plastic shell material flows out from an outlet and lighter grain of plastic foam material is sent through the outlet opening.