1. An image pickup device comprising: an image pickup means for taking an image including identification information for identifying a vehicle in a predetermined frame period; an image division means for dividing each of frame images obtained from the image pickup means into at least two images; a difference processing means for determining whether a difference is present between frame images divided by the image division means; and an image output means for successively outputting the divided frame images for each frame when the difference is determined to be present between the frame images by the difference processing means.