A method of preventing a multimedia copy is disclosed, by which an illegal use such as a distribution, a copy and the like without permission can be prevented through fast transformation and security management of multimedia downloaded via a network (Internet, wireless Internet, etc.) and by which an illegal inter-user-equipment copy of multimedia downloaded via a network (Internet, wireless Internet, etc.) can be prevented. The present invention includes the steps of dividing prescribed multimedia requested from a user equipment by a block unit, generating an encryption code for the user equipment by performing an encryption operation on at least one unique code for an identification of the user equipment, encrypting a prescribed block of the multimedia with the generated encryption code, and downloading the encrypted block.