In a wire-dot impact type printer, a single electric motor is employed for rotating a platen provided at a periphery thereof with a plurality of ink saturated members to thereby change a color to be applied to a printing paper, as well as for rotating tractors cooperated with feed rollers to thereby transport the printing paper in a predetermined direction. A transmission mechanism for transmitting rotational movement of the motor to the tractors comprises a switch disc rotated together with the motor and having a circular periphery thereof which is half toothed and half untoothed, and a clutch composed of a first rotating disc rotated due to engagement with the toothed half portion of the switch disc and a second rotating disc capable of rotating together with the first rotating disc being rotated in one direction to thereby cause the tractors to rotate for the paper feeding operation, but prevented from rotation when the first rotating unit is rotated in the opposite direction. The platen is rotatable in both directions by the reversible motor while the switch disc is positioned such that the first rotating disc of the clutch confronts the untoothed half portion of the switch and is not in mesh with the toothed half portion, which makes the tractors inoperative so that the printing paper remains standstill.