A color developer solution capable of inhibiting precipitation or tar-staining occurring in the processing tank or the roller rack, even when being processed rapidly or at low replenishing rate and a concentrated composition thereof is disclosed, comprising at least one selected from specified N-disubstituted hydroxylamine derivatives and at least one selected from specified N-monosubstituted hydroxylamine derivatives in a molar ratio falling within the range of 1000:1 to 1:1.
