A phase retarder including a layered inorganic compound-containing sheet or layered inorganic compound-containing film, the inorganic compound being selected from the group consisting of a clay mineral, a chalcogen compound, a zirconium phosphate compound, an oxyacid salt of a transition metal, a layered polysilicate, a metal oxyhalogenide, and an intercalary decoration thereof intercalated with ions or molecules between crystalline layer units, the inorganic compound having a mean particle size of 5000 nm or less and a stratified structure with a plurality of crystalline layer units wherein the phase retarder has a refractive index in the plane of the phase retarder that is different from a refractive index in the thickness direction of the phase retarder.