An image decoding method performed by a decoding device according to the present document comprises the steps of: obtaining, through a bitstream, image information including a motion information candidate index and residual information; deriving motion information of a current block on the basis of the motion information candidate index; deriving a prediction sample on the basis of the motion information; deriving, on the basis of residual syntax elements for a current residual coefficient in the current block, the current residual coefficient; deriving a residual sample on the basis of the current residual coefficient; and deriving a reconstruction sample of the current block on the basis of the prediction sample and the residual sample.