An information processing device includes: a memory; and a processor coupled to the memory and configured to: determine an angle of intra prediction for a block to be encoded in an image included in a video, and encode the block to be encoded using the angle of intra prediction; generate a bit value indicating an estimation result of the angle using a locally decoded pixel value of an encoded pixel adjacent to the block to be encoded; generate a bit string indicating the angle of intra prediction and generate flag information indicating whether a partial bit value of the bit string matches the bit value indicating an estimation result of the angle; and encode the flag information by a first encoding method and encode a remaining bit value of the bit string by a second encoding method.