A control device includes an execution unit, a determining unit, and a setting unit. The execution unit controls a printing unit to execute a multi-pass printing for a predetermined partial area of printing medium by executing sub scans and a prescribed number of times of main scans. In the main scan, a print head of the printing unit forms dots on the recording medium while being conveyed in a main scanning direction. In the sub-scan, the printing medium is conveyed in a sub-scanning direction. The determining unit determines an acceptable range based on an actual conveyance error in the sub-scanning direction. The setting unit sets the prescribed number to N when a representative value of predetermined partial area falls in the acceptable range, and sets the prescribed number to M being an integer greater than N when the representative value does not fall in the acceptable range.