An image processing apparatus for determining a main subject in an image comprising: a candidate detection unit configured to detect each of candidate images serving as candidates for a main subject for a plurality of frames of image data, wherein a candidate image defines an image area within a frame using position information in two-dimensions in screen coordinates; and a main subject determination unit configured to perform a positional state determination process of determining a positional state of each of the candidate images within a field of view and to obtain a degree of stable presence of the candidate images detected by the candidate detection unit within the image data spanning the plurality of frames from the positional state of each of the candidate images of each frame determined in the positional state determination process and to determine a main subject among the candidate images using the degree of stable presence, wherein the degree of stable presence is assumed to be a value indicating a cumulative time or a duration for which a candidate image is present within a predetermined distance threshold (Trs-diff) from a determination reference point, wherein the main subject determination unit determines from the candidate images the candidate image whose degree of stable presence reaches first a predetermined time value after a start of main subject determination as the main subject; and wherein the main subject determination unit is configured to determine a distance between each of the candidate images and the determination reference point set within the field of view as a positional state, the determination reference point being set according to an operation input. a candidate detection unit configured to detect each of candidate images serving as candidates for a main subject for a plurality of frames of image data, wherein a candidate image defines an image area within a frame using position information in two-dimensions in screen coordinates; and a main subject determination unit configured to perform a positional state determination process of determining a positional state of each of the candidate images within a field of view and to obtain a degree of stable presence of the candidate images detected by the candidate detection unit within the image data spanning the plurality of frames from the positional state of each of the candidate images of each frame determined in the positional state determination process and to determine a main subject among the candidate images using the degree of stable presence, wherein the degree of stable presence is assumed to be a value indicating a cumulative time or a duration for which a candidate image is present within a predetermined distance threshold (Trs-diff) from a determination reference point, wherein the main subject determination unit determines from the candidate images the candidate image whose degree of stable presence reaches first a predetermined time value after a start of main subject determination as the main subject; and wherein the main subject determination unit is configured to determine a distance between each of the candidate images and the determination reference point set within the field of view as a positional state, the determination reference point being set according to an operation input.