There are disclosed substituted thiazole dye compounds represented by the following Formula (I):Formula (I) ##STR1## wherein R.sub.1 represents a hydrogen atom or a group capable of substitution onto a benzene ring, n is an integer of 1 to 4, x represents a substitutent capable of forming a hydrogen bond with the hydrogen of --CONH--, R.sub.2 represents an electron-attractive substituent, R.sub.3 represents a group capable of substitution onto a thiazole ring, and R.sub.4 represents an aromatic group or an unsaturated heterocyclic group that bonds to the nitrogen atom at a carbon atom having an unsaturated linkage.The dye compounds provide a cyan color which is good in hues and possesses fastness to light and heat.