A face image is detected for each frame at a predetermined interval in moving image data, and the face image is traced using a frame in which the face image is detected and frames subsequent to the frame. A face sequence including an interval in which the face can be traced and motion velocity vectors of the face indicating a change in the position of the face image in the interval is generated based on the tracing result. Further, camera operation information about when the moving image data is acquired is generated from the frame image of the moving image data. When there is an overlap in the plurality of intervals in which the face images are traced, the face being tracked by the camera is determined using the face sequence and the camera operation information of each of the plurality of face images. The face determined to be tracked is then determined to be a key object.