Abstract: A thermal printer with a mechanism for preventing recording sheet from meandering. In order to perform the mechanism, the thermal printer is provided with a thermal line head, a platen roller and a holding shaft which is perpendicular to the surface of a recording sheet and rotatable about the axis thereof, the holding shaft being engaged with the thermal line head in such a manner that the thermal line head is horizontally swingable about the axis of the holding shaft with the positional relation between the recording sheet and the thermal line head unchanged, and subjected to frictional force to return the thermal line head to its standard position, so that printing operation is correctly carried out all times and the recording sheet is returned to its standard position, that is, the meandering of the recording sheet is prevented. This mechanism also can be performed by providing the thermal printer with a brake shoe engaged with the holding shaft as described above.