1. An image shooting device, comprising: a moving image shooting camera that shoots a moving image; a person detector that detects a person in the moving image and sets the person as a detected person; a person information memory that tracks a movement of the detected person and stores therein action of the detected person exhibited during a certain period of time in past; a person evaluator that evaluates the detected person based on the action of the detected person exhibited during the certain period of time in the past and give the detected person a score; a person determiner that determines that the detected person is a target person who a shooting person of the moving image intends to shoot, when the score of the detected person is higher than a predetermined value; and a shooting assist section that assists action of at least one of the shooting person and the target person so that the target person is included in the moving image, wherein the person evaluator increases the score of the detected person with increasing size of a face region of the detected person in a frame of the moving image during the certain period of time in the past; and wherein the person detector, the person evaluator, the person determiner and the shooting assist section are composed of a dedicated hardware or a computer that upon executing instructions stored on a non-transitory memory causes the shooting camera to perform the recited functions of the person detector, the person evaluator, the person determiner and the shooting assist section.