PURPOSE: To compensate the size of a picture, and to correct the distortion of the picture by curving each side of a screen frame only by proper quantity by using thermal force, etc.

CONSTITUTION: A fiber reinforced glass pipe 4 into which an electrochemical coil 3 is set up is inserted into each side of a frame body 2 made of a hollow square- shaped metallic pipe with size stacked onto the screen frame 1, and a correcting jig (a) is formed. The correcting jig (a) is placed and fixed onto the screen frame 1, the electrothermal coil 3 is conducted and the screen frame 1 is curved only by predetermined size through the frame body 2 by the generation of heat, and the distortion of the size of the picture previously measured is corrected. Pushing force through a mechanical method may be utilized as the means of the deformation of the screen frame.