An exchangeable tape unit having a tape spool and a printing tape wound over the tape spool. The printing tape can be prevented from being exposed to light, and the exchangeable tape unit being capable of maintaining stabilized quality for long duration without color change and quality change in a heat sensitive coloring layer formed in the printing tape, and being capable of facilitating storage. The heat sensitive coloring layer constituting the printing tape is positioned radially inwardly when winding the tape over a tape spool. Film sheets are affixed to upper and lower faces of a resultant tape roll of the printing tape. <IMAGE>
