The invention provides a colorant scattered well in resin by blending with dye of resin to relieve dispersed property of nigrosine dye and its shape is not easy to crumble and prepared method thereof, when prepared without forming bridging and departing with resin, thick color containing nigrosine dye uniformly at high density and prepared method thereof, and colouring composition containing nigrosine dye uniformly, crystallization temperature regulated easily, formed precisely and with good burnish exterior/surface, good photostability, less change of color phase with time and good machine physical property. The granulated colorant as a granulation product of a powdery nigrosine dye, that has a bulk density of 0.4 to 0.7 g/ml and a hardness of 1 to 20 N. A high-concentration master batchobtained by blending a granulated colorant and a thermoplastic resin, which comprises 25 to 100 parts by weight of a nigrosine dye in the granulated colorant per 100 parts by weight of the thermoplastic resin. A colored composition comprising a granulated colorant or high-concentration master batch and a thermoplastic resin or thermoplastic elastomer.