An ink set contains a first ink containing a compound in which a pyrazolone ring and a thiazole ring are bonded and a second ink containing a compound in which a pyrazolone ring and a pyridinedione ring are bonded. A thermal transfer recording sheet has a first ink layer containing a compound in which a pyrazolone ring and a thiazole ring are bonded and a second ink layer containing a compound in which a pyrazolone ring and a pyridinedione ring are bonded.

An object of the present invention is to provide a thermal transfer recording sheet that enables images having a wide color gamut, a high chroma, and good lightfastness, in which the degree of catalytic fading is reduced, to be formed. The thermal transfer recording sheet includes a base material and a colorant layer on the base material. The colorant layer includes a yellow dye layer, a magenta dye layer, and a cyan dye layer. The dye layers each include, as a dye, a compound having a specific structure.

An ink set for a thermal transfer sheet, comprising: a white ink; and a color ink having a color other than white, wherein the white ink contains a water-dispersible resin (A) and water, and the water-dispersible resin (A) has a thermal melting temperature of 100 C. or lower.