An image decoding device (200) includes: a decoding unit (210) configured to decode a first flag which is included in a slice header and controls enabling/disabling of PROF processing from encoded data; and an affine prediction signal generation unit (241F) configured to perform the PROF processing in a case where the first flag indicates that the PROF processing is enabled in a slice corresponding to the slice header, and generate a prediction signal without performing the PROF processing in a case where the first flag indicates that the PROF processing is disabled in a slice corresponding to the slice header.