A pixel interpolation processing apparatus and an image capturing apparatus are provided that are capable of performing a pixel interpolation process properly even when the pattern of color filter array is unknown. An imaging apparatus includes an imaging unit having a single-chip image sensor having four-color filter array for obtaining an image signal, and the imaging apparatus uses pixel data for a surrounding area around a target pixel to calculate a plurality of sets of correlation values in two directions orthogonal to each other, and determines the correlation direction based on these correlation values. The imaging apparatus obtains first to fourth color component pixel values for the target pixel relying on the fact that the high-frequency components of pixel signals in a direction orthogonal to a direction with high correlation have high correlation regardless of the color of color filters, thus allowing for performing pixel interpolation processing properly even if the four colors of color filters are unknown.