PURPOSE: To obtain a frame still picture without the deterioration of a picture quality, which is completely still even to a moving picture by displaying the still picture by storing picture information obtained by scanning-line-converting a high grade TV signal by the portion of one field and repeatedly reading the stored piece of picture information.

CONSTITUTION: In the case of displaying in a still picture, a still picture processing part 6 prohibits the writing of new data into a field memory 4 in the period of still display, repeatedly reads old data and set a still picture time signal b' to be the repeating of a field constituted by a line shown by the numeric characters of 1, 2, 3,.... Thus, one frame of a 525, 1:1 interlace signal and a 525, 2:1 interlace signal which are displayed by a double speed scanning monitor 12 and an NTSC monitor 10 are constituted by the numeric characters of 1, 2, 3,... existing within one field before (b') like respectively showing at (b') and (c'). Thus, the frame still picture without the deterioration of the picture which is completely still even to the moving picture is obtained.