There is provided a circularly polarizing plate that can prevent light leakage in an organic EL panel and can suppress the warping of the panel to reduce reflection unevenness in a panel surface. A circularly polarizing plate according to an embodiment of the present invention is used in an organic EL panel, and includes a polarizer and a retardation film directly bonded to the polarizer. In-plane retardations of the retardation film satisfy a relationship of Re(450)