A device, for processing each pixel signal output from a solid-state imaging device, has a determination processor and an interpolation processor. Each pixel is defined as a center pixel of a k×k matrix. The interpolation processor presumes which pixels have the same color as one another in the k×k matrix, according to the plurality of pixel-array patterns, and conducts a pixel interpolation in each case of presumed color arrangement according to the plurality of pixel-array patterns, so as to generate signal groups of presumed interpolation signals of the center pixel. The determination processor determines a pixel-array pattern in the k×k matrix to be a pattern selected from the plurality of pixel-array patterns. One of the signal groups that is generated according to the determined pixel-array pattern is selected as interpolation signals of the center pixel.