A continuous form printer is provided with two rotary encoders, corresponding to different paper feed intervals, and mounted coaxially on a drive shaft. The drive shaft drives a tractor for feeding the paper. The rotary encoders are read by photo-interruptor sensors, and the sensor signals are selected by a selector. The selector is able to select either one of the sensor signals generated by the encoders, or a signal formed by performing an AND operation on the two sensor signals. A controller controls a motor driving the drive shaft according to the selected signal, the selected signal corresponding to a chosen feeding interval. The controller is further able to precisely adjust the leading edge of the paper to a predetermined position based on the selected sensor signal, a known paper length, and a paper top sensor.