An image aligning method for a thermal imaging device includes picking up a thermal imaging medium that has a first surface and a second surface on which printing operations may be performed respectively from a medium container. An edge of the medium is fed a first distance from a heating element of a thermal printhead to a printing path. An image is formed on the first surface of the medium while proceeding the medium through the printing path. The thermal printhead is rotated to face the thermal printhead toward the second surface of the medium. The edge of the medium is fed the first distance from the heating element. An image is formed on the second surface of the medium while feeding the medium through the printing path.