An inter prediction method according to the present invention, which is performed by a decoding apparatus, comprises the steps of: configuring a reference picture set for a current picture; generating a virtual reference picture corresponding to an original reference picture in the reference picture set; deriving a motion vector for a current block in the current picture; and generating a prediction sample for the current block on the basis of the motion vector and the virtual reference picture. According to the present invention, the performance of inter prediction can be enhanced on the basis of a virtual reference picture having higher correlation with a current picture, and accordingly the amount of data allocated to a residual signal can be reduced and the overall coding efficiency can be improved.