An operator releases a locked state of a platen roller by a lock arm and causes the platen roller to be spaced apart from a thermal head with one step of operation. There is provided a thermal printer (1) including: a main body frame (2); a thermal head (4) mounted to the main body frame (2); a platen roller (6) disposed to be opposed to a printing surface (4a) of the thermal head (4), for sandwiching a thermal paper (15.) with the thermal head (4) to feed the thermal paper (15); a lock arm (5) swingably mounted to the main body frame (2), for locking the platen roller (6) with the main body frame (2) by pressing a shaft bearing (11) which rotatably supports the platen roller (6) against the thermal head (4); a swing arm (10) that supports the shaft bearing (11) of the platen roller (6), and swings between a lock position by the lock arm (5) and a release position apart from the lock arm (5); and a lever (16) movably provided to the swing arm (10), for releasing a locked state of the platen roller (6) by the lock arm (5) by an external force applied to a force point (18), in which a direction in which the force point (18) of the lever (16) moves when the locked state by the lock arm (5) is released is same as a swinging direction of the swing arm (10).