This invention relates to device for processing an image signal that can improve an image quality of a zoom image. Based on input image signal (Vin), an image-signal-processing section (110) produces output image signal (Vout) to display the zoom image with expansion rate of an image being changed consecutively around an arbitrary point specified by the user as a center. Each pixel data of the output image signal (Vout) is calculated by using coefficient data (Wi) produced by the coefficient production circuit (136). The coefficient production circuit (136) produces the coefficient data (Wi) based on not only the phase information (h, v) of each pixel but also the resolution adjustment information (f) and the noise suppression degree adjustment information (g) that the image quality adjustment information generation circuit (140) generates based on expansion rate (T) of the image, change rate (K) of the expansion rate of the image, and characteristics information (DR, MV) of the image.