The present invention relates to a device for driving rotary parts (06; 07) of printer. The driving device is arranged on side frames (11; 12) in the direction perpendicular the rotation shafts of the parts (06; 07) by means of a bearing device (14). The parts (06; 06) are rotatablely driven by a driving motor (81) of the parts, wherein the shaft collar (21; 22) of the parts (06; 07) do not traverse the profile line array of the side frames (11; 12) after installation. The driving device of the invention is characterized in that a rotor (84) of the driving motor (81) has torsion resistance and is detachably connected with the shaft collars (21; 22) of the components (06; 07). The driving device (14) is provided with a movable bearing base (34) for receiving the shaft collars (21; 22) of the components (06; 07). The baring base (34) is flatwise arranged at the inner side relative to the profile line array of the side frames (11; 12), and furthermore a stator (86) of the driving motor (81) can be rigidly but detachably connected with the bearing base (34) of the movable bearing base (34).