To obtain the subject compound having a high chroma and useful as a pigment for a high polymeric organic material, etc., industrially advantageously by reacting a specific diketopyrrolopyrrole with formic acid or carbon monoxide with a formic acid salt, etc., in the presence of a catalyst.

This diketopyrrolopyrrole carboxylic acid (ester, amide) expressed by formula II (X is X' or OH; Y is R3 or COX), and useful as a pigment for a high polymeric organic material, is obtained by reacting a diketopyrrolopyrrole expressed by formula I (A is a direct bond, phenylene, etc.; R1 to R3 are each H, a halogen, a 1-6C alkyl, a 5-6C cycloalkyl, a 1-6C alkoxyl, CF3, CN, NO2, etc.; Z is a halogen) with formic acid or carbon monoxide together with a compound of the formula; X'-H [X' is OR4 (R4 is a 1-18C alkyl, a phenyl which may be substituted, etc.) or NR5R6 (R5, R6 are each H, a group similar to R4, etc.), or an alkali (alkaline earth) metal formic acid salt in the presence of a catalyst (e.g.; palladium-triphenylphosphine complex).