PURPOSE: To provide a flexible PVC composition having suppressed smoking during combustion without deteriorating fire retardance, by mixing aluminum hydroxide, zinc borate, antimony trioxide and plasticizer therewith.

CONSTITUTION: The titled compsn. is prepd. by mixing 30W80pts.wt. aluminum hydroxide, 1W15pts.wt. zinc borate, 3W30pts.wt. antimony trioxide and 20W 100pts.wt. plasticizer (e.g., trimellitate ester and/or adipate polyester having a viscosity of 150cps or above) with 100pts.wt. PVC. By mixing these components, especially by using said plasticizers, the compsn. having suppressed smoking during combustion can be obtained without deteriorating inherent properties and fire retardance of PVC.