A printing unit comprises: a head unit including a head block having a thermal head provided therein; a platen unit including a platen roller configured to feed a recording sheet, the platen unit being separably combined with the head unit, wherein the head unit includes: a head frame including the head block removably mounted thereon, the head frame being configured to support the head block so that the head block is pivotable in a direction approaching and separating from the platen roller; an urging member interposed between the head frame and the head block, the urging member being configured to urge the thermal head toward the platen roller; a cutter mechanism mounted onto the head frame so as to be removable therefrom; and lock portions locked to the head block, which are configured to restrict a pivot of the head block toward the platen roller.