Relation between early hydration process and properties of fresh cement until setting was studied by using nine kinds of cements prepared from three commercial clinkers with various buring degree and three kinds of calcium sulfates, that is, natural gypsum, β-hemihydrate and anhydrite II. Ca(OH) 2 and CaSO 4 saturation ratio in liquid phase influenced remarkably on the early hydration process of cement paste rather than the hydraulic reactivity of clinker minerals themselves. Setting time well corresponded to the period of maximum Ca(OH) 2 saturation ratio in liquid phase which coincided also with the period of vivid hydration of alite. Soft burning of clinker so as to remain a little amount (0.5% level) of free lime was effective for shortening the setting time but strength at longer age was slightly inferior to that of cement from well burnt linker. Though the setting time was shortened in the order of natural gypsum, β-hemihydrate and anhydrite II in cement from well burnt clinker, no remarkable influence of the kind of calcium sulfate was recognized in cement from poorly burnt clinker.