A video signal processing circuit, which performs contour adjustment by means of digital signal processing, is applicable to a viewfinder apparatus for a television camera and an image monitor apparatus, which can be operated both in an NTSC/PAL system and an HDTV system. The video signal processing circuit includes a contour-adjusting circuit for performing contour adjustment by peaking R, G, and B signals or by peaking a Y signal in an HDTV system and for outputting at least one adjusted signal; an inverse matrix transforming circuit for separating, by performing inverse matrix transformation, the R, G, and B signals from the adjusted Y signal, a Pr signal, and a Pb signal and for outputting the separated R, G, and B signals; and a selecting circuit for selecting, in accordance with the type of input video signals, either the R, G, and B signals in which the contour adjustment is performed or the Y signal, in which the contour adjustment is performed, and the Pr signal and the Pb signal, in which the contour adjustment is not performed.