PROBLEM TO BE SOLVED: To provide a process for industrially producing compounds (1a) which are useful as inhibitors of activated blood coagulation factor X.SOLUTION: Hydrazide derivative compounds (4) are obtained by condensing carboxylic acid derivatives, which are obtained by acid hydrolysis of carboxylic acid ester derivatives using 4 or more N (normality) acid aqueous solutions, with di(methyl) amine or the salt thereof in the presence of a condensation agent. Then compounds (1) are produced by treating the compounds (4) with orthoformic acid esters or orthoacetic acid esters in a polar aprotic solvent in the presence of Lewis acid.【課題】活性化血液凝固第Ｘ因子の阻害剤として有用な化合物（１ａ）の工業的な製造方法を提供すること。【解決手段】カルボン酸エステル誘導体を、４規定（４Ｎ）以上の酸水溶液を使用する酸加水分解から得られる、カルボン酸誘導体に、縮合剤の存在下、ジ（メチル）アミン又はその塩と縮合させて得られるヒドラジド誘導体化合物（４）を、非プロトン性極性溶媒中、ルイス酸の存在下に、オルトギ酸エステル又はオルト酢酸エステルと処理して化合物（１）を製造する。【選択図】なし
