Coding processing performed by an image coding device (100) includes: processing (S133) of performing coding by leaving surplus bit(s), when the digit number B of binary data of the difference value between (a) a value of a to-be-coded pixel and (b) a prediction value is smaller than the predetermined bit number M; and processing (S133) of performing coding by using the surplus bit(s), when the digit number B is greater than M and there are the surplus bit(s). Pieces of coded data each having a predetermined coding amount are generated, by performing processing for each of consecutive T pixels so as to perform the coding processing for each of U pixels among the consecutive T pixels (S136).