In this paper, the foaming method of polymer concrete was studied. The pre-composition of polymer concrete consisted of unsaturated polyester as a binder material 15 ~ 50 wt%, sand 0 ~ 80 wt%, filler 5 ~ 50 wt%, and foaming agent 0.1 ~ 0.5 wt%. The pre-composition was heated at 100 ~ 200 ℃ for 30 ~ 120 minutes, which thermal treatment caused hardening of unsaturated polyester and cracking of foaming agent. The foamed polymer concrete showed low thermal transfer coefficent together with good mechanical properties.