PURPOSE: To prevent degradation of picture quality of a non-interlace signal even if discontinuity of a picture occurs in a frame, field or the like of an interlace signal.

CONSTITUTION: This system is provided with a video synthesizing means 1 which synthesizes in frame an interlace signal of two or three fields and an non-interlace signal of one frame, and a scene change detecting means 2 which compares field signals of the same kind among interlace signals of successive four field and detects a discontinuity point of a picture, the video synthesizing means 1 excludes a field signal discriminated as discontinuity from frame synthesizing based on detected information of a discontinuity point. Also, this system is provided with a video synthesizing means 3 and a channel switching storage means 4 which stores input timing of a channel switching signal relating to an interlace signal, the video synthesizing means 3 excludes a field signal discriminated as discontinuity from frame synthesizing by the channel storage means 4 at the time of frame synthesizing.