An image processing apparatus acquires a plurality of pieces of image data sequentially outputted from an imager and, in accordance with reception of an image capturing instruction to capture a still image, specify as image data to be processed a plurality of pieces of image data in a period that includes a timing at which the still image is captured. The image processing apparatus, based on an action of a subject estimated using the image data to be processed, add information that indicates the action of the subject to data of the still image.