A flat panel for a cathode ray tube of the present invention includes a faceplate having a useful screen for displaying an image; a skirt portion which extends from a perimeter of the faceplate and has a seal edge; and a blend round portion joining the faceplate with the skirt portion, wherein when an average outer curvature radius R1 and an average inner curvature radius R2 of the faceplate are equal to or greater than 10,000 mm, an overall height H of the faceplate satisfies a following relationship: T1+10≦H≦D×0.12 where T1 and D are a face center thickness of the faceplate and a diagonal length of the useful screen, respectively.