To provide a method for producing a monoacyl compound in a simple operation with a high selectivity and at high purity without using a large amount of a diamine compound compared with the conventional method which uses a large amount of the diamine compound and requires a complicated purification step in isolating the monoacyl compound in order to produce the monoacyl compound by reacting the diamine compound with an acylating agent.

The method for producing a monoacyl compound comprises reacting a diamine compound with an acid to obtain a diamine salt by the neutralization of both of the two amino groups of the diamine compound with the acid, then reacting the diamine salt with a base to form a monoamine salt by the conversion of one of the amino groups forming the salt of the diamine salt to an amino group, and subsequently acylating the monoamine salt with an acylating agent.