An image receptor for a thermal transfer ink for use in a tape printer, which is used with it contained in a cassette in the tape printer, and which comprises an image receptor body (10) and a release material (15) adhered to one side of the image receptor body, and has a total thickness of 80 to 200 .mu.m, characterized in that, when the image receptor is subjected to measurement wherein, with use of a measuring device which comprises a female member (1) having a V-shaped groove (2), and a male member (3) having a V-shaped protrusion (4) capable of engaging with the V-shaped groove (2) and having a radius of rounding of 0.1 to 0.3 mm at the leading edge (5) of the V-shaped protrusion, the image receptor is held between the female member (1) and the male member (3) and a load of 30 to 2,000 g/cm.sup.2 is applied thereto for 10 seconds, a lift is not produced in the image receptor at a bending angle .beta. (which means the supplementary angle of the angle .alpha. of the V-shaped groove (2) in the female member (1) of the measuring device used) of at least 110 degrees, in order to avoid occurrence of lifts in the image receptor during traveling of the image receptor.