An animation data sales mediation method, an animation data sales mediation system and so on are capable of providing large capacity data such as animation data by a large capacity storage medium in advance, rendering the time required for transfer of the data via the network extremely short by passing a key code for viewing the animation data via the network, rendering the labor and costs required for sales of the animation data extremely low, and providing the latest unauthorized copy technology to the animation data. The animation data sales mediation system has the steps of having a user terminal send to a large capacity data sales server an online access code corresponding to the large capacity data one to one, having the large capacity data sales server send the key code to the user terminal, having the user terminal encrypt and store the key code, and having the animation data used by using the key code.