1. An apparatus for decoding a current block in a current frame by using an inter prediction, the apparatus comprising: a decoding unit configured to extract a first identification information from a bitstream, wherein the first identification information indicates whether motion information of the current block is set as one of a plurality of motion information candidates, wherein the motion information includes a motion vector of the current block and a reference frame index of the current block, and reconstruct a quantized frequency residual block of the current block from the bitstream; a dequantization and inverse transform unit configured to dequantize and inversely transform the quantized frequency residual block to reconstruct a residual block of the current block; an inter prediction unit configured to perform the inter prediction by, when the first identification information indicates that the motion information of the current block is set as one of the plurality of motion information candidates, generating the plurality of motion information candidates of the current block from neighboring blocks of the current block, wherein the neighboring blocks are adjacent to the current block and are located in the current frame, selecting a motion information candidate from the plurality of motion information candidates based on a second identification information, the second identification information being decoded from the bitstream, reconstructing the motion information of the current block as the selected motion information candidate, and generating an inter-predicted block of the current block by using the reconstructed motion information of the current block; and an addition unit configured to add the inter-predicted block to the residual block so as to reconstruct the current block, wherein when the first identification information doesn't indicate that the motion information of the current block is set as one of the plurality of motion information candidates, the inter prediction unit is configured to perform the inter prediction by generating the inter-predicted block of the current block by using a decoded motion information of the current block, wherein the decoded motion information of the current block has been extracted from the bitstream and decoded, wherein the plurality of motion-information candidates are generated by using motion information items of the neighboring blocks of the current block, wherein the motion information items include each motion vector of each of the neighboring blocks and each reference frame index of said each of the neighboring blocks, and wherein the neighboring blocks include a neighboring block including a sample located just above a left sample of a top-left sample of the current block, and a neighboring block including a sample located on a right side just above a top-right sample of the current block.