An imaging device includes an imaging unit capturing an image of a subject, and tracks, through images captured in time series, an area in which a specific target appears. The device includes a parameter acquiring unit acquiring a photographic parameter from the imaging unit, a target area determining unit determining an area of a captured image including the specific target as a target area, a track area adjusting unit setting a track frame for a track area to track the target area including the specific target and adjusting a size of the track frame based on the photographic parameter, and a track area searching unit searching the captured image for the track area, while moving the size-adjusted track frame, based on a similarity between a characteristic amount of the track area of a current captured image and that of the target area of a previous captured image.