A determination device generates, based on a first captured image captured by a first image capturing device mounted on a moving object, a shape of a subject (one of subjects) included in the first captured image. The determination device estimates the location of the shape of the subject after specific time based on the location of the shape of the subject and a moving speed. The determination device extracts the shape of the subject from a second captured image captured by a second image capturing device mounted on the moving object; compares the location of the shape of the subject extracted from the second captured image with the location of the shape of the subject estimated from the first captured image; and performs determination related to a moving state of the subject.