An image signal processing apparatus includes an inputting unit, an electrical image stabilizing unit, and a compression encoding unit. The inputting unit is arranged to input an image signal representing a sequence of images of a subject produced by an image sensing unit. The electrical image stabilizing unit is arranged to detect unintentional movement of the image caused by shaking of an image sensor unit on the basis of the image signal and to correct the image signal, after the input signal is input by the input unit, by removing the effect of the unintentional movement, so as to yield a corrected sequence of images in which a position of the subject is stabilized. The compression encoding unit is arranged to interpicture encode the image signal stabilized by the electrical image stabilizing unit.