A motion information storing method and a TMVP deriving method using the motion information storing method are provided. The motion information storing method includes a step of determining a representative block out of blocks of a motion data storage unit in a co-located picture with a current picture and a step of storing motion information of the representative block as motion information of the motion data storage unit, wherein the motion information of the representative block is used as motion information of the blocks included in the motion data storage unit.