A moving image distribution system, wherein the user can view content moving images at no charge, and the provider of the content moving images can prevent a drain of the moving image contents and can protect the copy right thereof, as a copy right holder, without fail. The moving images are divided, along a time axis, into two master and slave nonreproducible moving image files. The slave moving image file (small file) is encrypted based on CM file data in which a predetermined CM element has been incorporated. In response to a reproduction request of a user terminal that possesses the master moving image file (main file) in advance, the slave moving image file is distributed with the CM moving images to the user terminal via a network line such as the Internet.