A CPU of an imaging device of the present invention causes an interval moving image to be captured for each interval photographing, selects frames to be stored as still images from among a plurality of frames constituting the interval moving image based on a face image, blurring, and the presence or absence of a change, and causes these selected still images to be stored in association with the interval moving image. When an amount of data exceeding that for a preset storage time length is recorded, the CPU first deletes low-grade interval moving images. Then, if this is not enough, the CPU deletes low-grade still images, and thereby retains an image file (a mixture of moving images and still images) within the desired time length.