Being able to reduce shunt current losses through the electrolyte in the slit, it is possible to improve the heat dissipation of the electrolyte solution, there is provided a frame for use in a cell of a redox flow battery capable of suppressing the generation of distortions of the slit forming portion. Les as frames used in the cell of the redox flow cell, by connecting with the openings formed on the inner side of the frame and manifold electrolyte flow, and said manifold said opening, of said electrolyte solution between the manifold and the opening having a slit for forming a flow passage, and the slit is less than the frame having at least one valley, at least one radius of curvature of the bent portion in at least 2.0 ㎜ 200 ㎜.