Existing methods of evaluation based on the undrained behavior cannot always provide a realistic prediction to post-liquefaction deformation and strength behavior of saturated sands. Redistribution of water content or void redistribution in saturated sand during a shearing application is referred to as the water absorption in shear. Previous experimental facts show that occurrence of the water absorption in shear after an earthquake is one of the main reasons why large lateral flow slides happened in liquefied looser to medium dense sands. A new constitutive model considering effect of the water absorption in shear has been developed for description of the post-liquefaction stress-strain response of saturated sand subjected to an application of monotonically shearing in any arbitrary drainage condition. Essential effectiveness of the proposed constitutive model was confirmed experimentally.