A printer module for use in a printer apparatus having a rotationally openable lid includes a fixed blade module having a fixed blade, a movable blade module having a movable blade and configured to be joined to the fixed blade module such that the movable blade and the fixed blade face each other, and a positioning unit configured to position the movable blade module relative to the fixed blade module such that an angle between the movable blade and the fixed blade becomes optimum upon joining the movable blade module to the fixed blade module, wherein the movable blade module is configured to be movable relative to the rotationally openable lid upon being mounted on the rotationally openable lid of the printer apparatus.