Image coding method, image decoding method, image coding apparatus, and image decoding apparatus

An image decoding apparatus comprising:

• a decoding unit configured to:
• (i) decode a first flag from a coded signal, the first flag indicating whether or not a motion vector can be used for decoding a current frame including a current block;
• (ii) decode a second flag when the current block is coded in skip mode and the first flag indicates that a motion vector can be used, the second flag indicating whether or not a motion vector is used for decoding the current block;
• (iii) decode, from the coded signal, index information indicating a motion vector to be selected, when both (a) the first flag indicates that a motion vector can be used and (b) the second flag indicates that a motion vector is used for the decoding of the current block in the skip mode;
• and
• (iv) decode the current block using the motion vector selected based on the index information,
• wherein the second flag indicating that the motion vector is not used for decoding the current block is decoded when the first flag does not indicate that the motion vector can be used for decoding the current frame.