1. A method of fitting a virtual item, the method comprising: determining whether a user is located in an experience area; loading a three-dimensional (3D) standard avatar corresponding to setting information input by the user when the user is located in the experience area; obtaining a depth image of the user corresponding to a preset posture; transforming the 3D standard avatar into a user avatar reflecting body characteristics of the user using the depth image of the user; fitting a virtual item selected by the user to the user avatar; applying a motion of the user changing in real time to the user avatar to which the virtual item is fitted; calculating transformation of the virtual item when the motion of the user is applied to the user avatar; synthesizing a result of rendering of the transformed virtual item with a real color image of the user captured by a camera; and displaying a result image rendered based on the synthesized result, wherein the calculating comprises reverse-reflecting calculated difference of top and bottom of shoulder in a result of retargeting with respect to motion of the user avatar, and controlling motion information of a joint to offset difference error.