A system for detecting poor video editing detects a television (TV) image signal. When a TV image originates from a film signal rather than a video signal, a de-interlacing device performs a de-interlacing at a film signal mode to thereby increase a vertical resolution of a TV image signal. A sawtooth detector can detect a poor video editing, which causes a sawtooth occurrence to TV image signals, on an unbroadcasted TV image signal. Accordingly, the poor video editing is found in advance. Also, the invention uses a scene change in combination with the sawtooth detector to thereby avoid a poor edited image and obtain a preferred image quality.