A printer for printing characters on a recording medium includes, a printing drum provided on a first portion and a second portion of the outer periphery thereof respectively with a first set of type faces and a second set of type faces, the first set of type faces being adapted to print characters of odd or even digit positions in a row of characters to be printed while the second set of type faces is adapted to print remaining characters of even or odd digit positions in the row of characters to be printed, the top surface of each of the first and second sets of type faces being retracted from the outer periphery of the printing drum, and each face being provided with a resilient member on at least a part of circumference thereof; a hammer unit positioned in the printing drum and provided with a plurality of hammers, the hammers being adapted to selectively thrust faces of the first and second sets through the outer periphery of the printing drum to bring the hammers in pressure contact with the recording medium; a roller integral with the hammer unit and adapted to press the type faces of the first and second sets thereby causing the faces to project from the outer periphery of the printing drum; and an ink roller for applying ink onto the faces of the first and second sets maintained in projecting position by means of the roller.