Bentonite is a clay made up almost entirely of smectite minerals, montmorillonite. Purified bentonite is applied for various industrial uses. To develop purified bentonite, it were prepared by sedimentation method using various addition agent from domestic bentonite and physical properties on these bentonite were investigated. Crystal structure, chemical composition and particle size distribution of DY-5 and purified bentonite were elucidated XRF, XRD, EDX, TG-DTA and paritcle size analyzer The chemical and the physical properties of purified bentonite, were effected by sedimentation method using various addition agent.