A cathode ray tube comprises a panel having a fluorescent formed on an inner surface thereof; a funnel connected to the panel; an electron gun housed in the funnel emitting electron beams; a deflection yoke for deflecting the electron beams in horizontal and vertical directions; a shadow mask for selecting colors of the electron beams; and a mask frame for supporting the shadow mask, in which an outer surface of the panel is substantially flat and an inner surface has a designated curvature, and a radius of curvature from a center of the shadow mask in a major-axis, minor-axis and diagonal-axis direction is substantially same.