This paper describes the effects of temperature increase of fill induced by cement hydration on the unconfined compressive strength of foamed mixture lightweight soils at a construction site. The specimen was cured at curing temperatures based on the temperatures(10 to 95℃) obtained from model and field tests before unconfined compression testing, to investigate the effects of temperature increase due to cement hydration on the unconfined compressive strength of foamed mixture lightweight soils. The unconfined compressive strengths of the specimen subjected to high curing temperature histories were compared with those of the specimen cured at 20℃. Unconfined compressive strength decreases significantly under high temperature histories. The unconfined compressive strength cured for 28days at high curing temperature(10 to 95℃) is about 70% that of specimens cured at 20℃. Finally, we find, that revaluation of the design strength is necessary and temperature management is important when foamed mixture lightweight soils are constructed.