Provided are a water treatment system and a water treatment process, which are capable of reproducing water containing salts with high water recovery. In the water treatment system (400) and the water treatment process of the present invention, after a calcium scale inhibitor and a silica scale inhibitor are supplied to water to be treated containing Ca ions, SO4 ions, carbonate ions, and silica, and the water to be treated is separated in a second demineralizing section (210) into second concentrated water in which the Ca ions, the SO4 ions, the carbonate ions, and the silica are concentrated and treated water. In a second crystallizing section (220), seed crystals of gypsum are supplied to the second concentrated water, whereby gypsum is crystallized and removed from the second concentrated water.