Image encoding method and image encoding apparatus

An image encoding apparatus for encoding units that are included in a picture, the image encoding apparatus comprising:

• control circuitry;
• and
• a storage accessible from the control circuitry,
• wherein the control circuitry executes:
• generating a first flag indicating whether or not a removal time of encoded data from a buffer by a hypothetical decoder is set per unit, the buffer being for storing the encoded data;
• generating a second flag indicating whether an interval between removal times of the units is constant or arbitrary when the removal times are set per unit;
• and
• generating an encoded bitstream including the encoded data, the first flag, and the second flag.