A control device includes a shape information storage storing shape information to be plotted, a stroke generation unit generating first and second stroke data having transmission start and end coordinates of first and second strokes, a scanning start time computation unit determining scanning start time of the second stroke by adjusting, when selecting first and second points having a shortest distance, a waiting time to scan the second stroke, a traveling rate from the transmission end coordinates of the first stroke to the transmission start coordinates of the second stroke, and scanning rates of scanning the first and second strokes to have a desired time interval between the selected points, a plotting instruction generation unit generating plotting instructions including the scanning start time of the second stroke and the transmission start and end coordinates of the first and second strokes, a plotting instruction storage storing the plotting instructions, and a plotting instruction execution unit executing the plotting instructions.