Gypsum is an important building material used to provide fire resistance to constructions by reducing their temperature rises. As the hardened gypsum is exposed to fire, evaporation of both the free water and the chemical bond water is easier than that in the hardened cement paste. The purpose of this study is to investigate the utilizability of gypsum to prevent spalling failure of cement concrete exposed to fire. This paper reports the hydration behavior and fire-resistance property of a controled ordinary portland cement mortar(C) and gypsum-cement mortars with 4 types of gypsum such as anhydrite(0G), ${alpha}$-hemihydrate(AG), ${eta}$-hemihydrate(BG) and dihydrite(2G). As a results, it is found that the compressive strength of a controled ordinary portland cement mortar is higher than those of 4 types gypsum-cement mortars. However, it is found that gypsum-cement mortars are more effective to prevent the explosive spalling failure under standard fire condition than a controled ordinary portland cement mortar, and the thicker the thickness of specimen is, the more significant the influence of gypsum is.