To provide a cutting mechanism comprising a cutter for cutting a long printing medium such as a tape and a tube, a motor generating a predetermined drive force, and a drive force transmitting part transmitting the drive force from the motor to the cutter, which cuts a printing medium in a short period of time, and a printer.

The cutter 67 cuts a printing medium printed by a printing part 2. The motor 61 generates a predetermined drive force. The drive force transmitting part transmits the drive force from the motor 61 to the cutter 67. A second gear 64 includes a boss 64a in an eccentric position and is rotated by the drive force generated by the motor 61 via a first gear 63. A cutter lever 65 includes a curved cam groove 65a into which the boss 64a is inserted and is moved based on the curved shape of the cam groove 65a by the movement of the boss 64a when the second gear 64 rotates, to press the cutter 67. Thus, even when the drive speed of the motor 61 is increased, cutting time needed for cutting the printing medium can be secured. As a result, the printing medium can be cut in a shorter time than before, while improving working efficiency.