A shopping-mall system utilizing user-based avatars comprises a terminal for transmitting user's three-dimensional image data through a wired or wireless communication network and then selecting any one of items provided through the wired or wireless communication network to receive an avatar image wearing the selected item and to transmit purchase specification information for purchasing the selected item. An avatar creation server receives the three-dimensional image data from the terminal and then creates an avatar image. A three-dimensional shopping-mall server puts any one item selected among a plurality of items stored therein on the avatar image created by the avatar creation server to provide the terminal with the avatar image wearing the item, and then performs an electronic commerce transaction with the terminal on the receipt of the purchase specification information of the selected item.