Fluidized bed medium separation (FBMS) was applied for gravity separation of plastics containing or not Cl for recycle of home electric appliance shredder residue. We employed mixtures of glass beads (G.B.) and polystyrene particles (PS.) with various mixing ratios as fluidizing particles. Floating and sinking of the plastics were examined by changing the bulk volume fraction and the superficial velocity u(o). The plastics were almost completely separated at the conditions of G.B.: P.S.=8: 2 and u(o)/u(mf) = 1.5 where u(mf) is the minimum fluidization velocity. Similar experiments were carried out by changing dimensional parameters of plastics, such as equivalent volume diameter D-v, flatness ratio R-f and aspect ratio R-a. As a result, it was found that influence of D-v on float-sink behavior was the highest and contribution ratio of D-v was about 75%.