A printing apparatus comprises a step motor (51) for feeding paper in a paper feed direction, an interface (68) for inputting printing data including bar code data, an image buffer (63) for storing bit image data representing at least first and second bar codes which correspond to the same bar code data input by the interface (68), a thermal head (47) having a row of heating elements perpendicular to the paper feed direction for printing the bit image data stored in the image buffer (63) in units of lines on the paper, and a control circuit (60, 70, 73, 74) for driving the step motor (51) to feed the paper in order to print the bit image data, and for driving the thermal head (47) each time the paper is fed by a preset amount. In the printing apparatus, the first and second bar codes represented by the bit image data are constituted by a set of bar code elements parallel to the paper feed direction and a set of bar code elements perpendicular thereto, respectively, and the control circuit (60, 70, 73, 74) drives the step motor (51) to feed the paper at a first speed in order to print a portion of the bit image data corresponding to the first bar code and at a second speed slower than the first speed in order to print a portion of the bit image data corresponding to the second bar code.