We Claim:
1. A video image decoding device comprising: a variable length decoder that performs a variable-length decoding process on coded data multiplexed into a bitstream to obtain coding mode which indicates a prediction process performed to generate a prediction image and index information which specifies a motion vector for a coding block; and a motion compensator that performs a motion compensation prediction process on said coding block to generate a prediction image using a motion vector selected from one or more selectable motion vector candidates when said coding mode indicates inter prediction, said motion compensator selecting said motion vector from said motion vector candidates according to said index information; wherein said motion compensator prepares a list of said motion vector candidates including one or more spatial motion vectors which are obtained from a decoded block located around said coding block and/or a temporal motion vector which is obtained from a different picture which can be referred to by said coding block, said motion vector candidates being listed in accordance with a predetermined order, and said index information specifying a position in which one of said motion vector candidates exists within said list.
2. A video image decoding method comprising: performing a variable-length decoding process on coded data multiplexed into a bitstream to obtain coding mode which indicates a prediction process performed to generate a prediction image and index information which specifies a motion vector for a coding block; and performing a motion compensation prediction process on said coding block to generate a prediction image using a motion vector selected from one or more selectable motion vector candidates when said coding mode indicates inter prediction, said motion vector being selected from said motion vector candidates according to said index information; wherein said motion vector candidates includes one or more spatial motion vectors which are obtained from a decoded block located around said coding block and/or a temporal motion vector which is obtained from a decoded picture which can be referred to by said coding block, said motion vector candidates being listed in accordance with a predetermined order, and said

index information specifying a position in which one of said motion vector candidates exists within said list.
3. A video image encoding device comprising: a motion compensator that performs a motion compensation prediction process on a coding block to generate a prediction image using a motion vector selected from one or more selectable motion vector candidates, said motion compensator selecting said motion vector from said motion vector candidates; a variable encoder that performs a variable-coding process to generate coding mode which indicates a prediction process performed to generate said prediction image and index information which specifies selected one of said motion vector candidates; wherein said motion compensator prepares a list of said motion vector candidates including one or more spatial motion vectors which is obtained from a coded block located around said coding block and/or a temporal motion vector which is obtained from a different picture which can be referred to by said coding block, said motion vector candidates being listed in accordance with a predetermined order, and said index information specifying a position in which one of said motion vector candidates exists within said list.
4. A video image encoding method comprising: performing a motion compensation prediction process on a coding block to generate a prediction image using a motion vector selected from one or more selectable motion vector candidates, said motion compensator selecting said motion vector from said motion vector candidates; performing a variable-coding process to generate coding mode which indicates a prediction process performed to generate said prediction image and index information which specifies selected one of said motion vector candidates; wherein said motion compensator prepares a list of said motion vector candidates including one or more spatial motion vectors which is obtained from a coded block located around said coding block and/or a temporal motion vector which is obtained from a different picture which can be referred to by said coding block, said motion vector candidates being listed in accordance with a predetermined order, and said index information specifies a position in which one of said motion vector candidates exists within said list.
Dated this 30 day of July 2018