To obtain the subject compound useful as an intermediate for producing diazines as an insecticide in a high yield and purity and in an economically advantageous way by reacting 2-amidinopropane hydrochloride with methyl acetoacetate in a dry medium.

In (A) a dry medium such as an aliphatic hydrocarbon solvent [e.g. (cyclo)hexane, heptane, octane], optionally in the presence of (B) a methanolic base, (C) 2-amidinopropane hydrochloride of the formula is reacted with (D) methyl acetoacetate, and, as necessary, the water produced during the reaction is removed by azeotropic distillation, thus obtaining the objective compound. The above reaction is preferably carried out as follows: the component C is first added to dry methanol and both the components C and D are used in the molar ratio C/D of (1:1) to (1:1.05).