A novel printing apparatus comprises a single drive motor, rotational drive force reduction gears, a drive gear fixedly mounted on a rotary shaft and normally rotated by the drive motor through reduction gears, a base frame rotatably support the rotary shaft, a swingable support plate swingably supported to the rotary shaft, a printing drum rotatably supported to the swingable support plate and threadedly engaged with the drive gear, printing web feeding means for feeding printing web to face the drum, biasing means for biasing the printing drum in the direction opposite to the fed printing web, and novel forcible stopping means for preventing the drum to rotate around its own axis to thereby allow the drum to rotate around the rotary shaft against the biasing means while engaging with the drive shaft.