PURPOSE: To improve stability to light without degrading the hue and purity of organic base material, particularly coloring matter or dye by using a specific stabilizer which has high solubility to organic solvents and high miscibility with organic base material.

CONSTITUTION: The complex of the formula [M is Cu, Co, Ni, Pd, Pt; Cat is one bivalent cation, two univalent cations; X is S, formula II; R1, R2 are CN, COR3, COOR4, CONR5R6, SO2R7, non-metal atom groups necessary for forming 5 to 6 rings by mutually bonding; R3, R4, R7 are respectively (un) substituted alkyl of C1-20,aryl of C6-36, R5, R6 are synonyms of H, R3; n is 1, 2] is let to coexist, as a stabilizing agent, with organic base material which has absorption maximum at about 300 to 800mμ. Thereby, the stability to light of the dye formed by the reaction of aromatic primary amine developing agent and color coupler is improved.