Abstract: A multi-color development thermal printer develops simultaneously magenta, cyan, and black using a line-type thermal head on a recording medium, which develops magenta at a low temperature, cyan at an intermediate temperature, and black at a high temperature. One line's worth of first two-color development bit data for developing magenta and black, and one line's worth of second two-color development bit data for developing cyan and black, are generated based on one line's worth of three-color development bit data. During a period required for a recording operation of one line by the line-type thermal head, the line-type thermal head performs a first recording operation in accordance with one line's worth of the first two-color development bit data, and then a second recording operation in accordance with one line's worth of the second two-color development bit data.