A printer device comprising: a print head that prints on a recording sheet; a platen roller supported by a frame; an energizing spring, which is provided between the frame and the print head and presses the print head on the side of the platen roller; and an opening/closing arm supported so as to pivot and move with respect to the frame with the arm rotation axis as the center. The printer device is characterized in that the area of contact between the opening/closing arm and the platen bearing of the platen roller is on the opposite side, with respect to a line tying the center of the arm rotation axis to the center of the platen bearing, from the side where the print head is provided.