A printer having an opening/closing cover for providing access to a roll paper compartment, a peeler mechanism for peeling printed labels from a web and for dispensing the peeled printed labels from the printer and an opening and closing mechanism 50 which locks and unlocks the cover and a peeler unit 10 of the peeler mechanism in response to the manual operation of a manual operating member such as a release button 17 with a single easy operation. When the release button 17 is depressed into a first operating position 17B, a lock lever 52 of the opening/closing mechanism 50 slides from a locked position 52A to a released position 52B to disengage the lock lever 52 thus unlocking the opening/closing cover 9. At the same time, the sliding lock lever 52 pushes engaging claws 74a, 73a that lock or unlocks the peeler unit 10. When the cover release button 17 is further depressed into a second operating position 17C, the lock lever 52 swings and a cover-lifting surface 54 on the lock lever 52 pushes the opening/closing cover 9 up causing the unlocked opening/closing cover 9 to move into a raised open position. Simply pushing the cover release button 17 thus unlocks and raises the opening/closing cover 9, and unlocks the peeler unit 10.