1. A data processing device comprising: a display unit; a touch panel unit that detects a touch operation and outputs detection information; a flick detection unit that detects a direction of a flick from the detection information of the touch panel unit; a label determination unit that determines a label representing a category to which content belongs, based on the direction of the flick; and a teacher data generation unit that displays the content on the display unit, and generates teacher data including the content and the label determined by the label determination unit.