A polarizer includes a reflective polarizer main body and an Rth compensation layer. The reflective polarizer main body includes a repetitively laminated structure, the repetitively laminated structure including two layers of different refractive indices repetitively disposed on one another. The Rth phase compensation layer is disposed at one side of the reflective polarizer main body. The Rth phase compensation layer is configured to compensate for a phase difference in an Rth direction.