A thermal printer is provided including a cable which connects a main board and a recording head to form an image on a print medium by heating both surfaces of the print medium. The thermal printer includes a rotating unit rotatably installed within a frame. The thermal printer also includes a recording head, a support member, and a main board installed on the frame substantially above the first surface of the print medium. The main board applies power and provides image data to the recording head. A flexible cable is disposed on one side or both sides of the print medium so as to not to interfere with a transfer of the print medium and a reciprocating rotation of the recording head. The flexible cable connects the main board and the recording head. A control guide is disposed on a path where the flexible cable moves within the frame to control a degree to which the flexible cable is loosened when the recording head is located at a certain position.