Into 50 ml of dimethylformamide were added 1.73 g of 6-hydroxycarbostyril, 1.8 g of K2CO3 and 0.5 g of KI. The mixture was heating at 60°-70° C. under stirring, then 3.2 g of N-(2-hydroxyethyl)-N-(4-chlorobutyryl)cyclohexylamine was added dropwise gradually thereto. After the addition operation, the reaction mixture was further stirred at the same temperature for 4 hours. Then the solvent was removed by distillation and the residue thus obtained was dissolved in 200 ml of chloroform and the chloroform layer was washed with a diluted hydrochloric acid, 1% Na OH aqueous solution and water in this order, then dried with anhydrous sodium sulfate. The drying agent was removed by filtration, and the mother liquid was concentrated, then the residue thus obtained was crystallized with petroleum ether. The crystals thus obtained was recrystallized from chloroform-petroleum ether to obtain 0.5 g of 6-{3-[N-(2-hydroxyethyl)-N-cyclohexylaminocarbonyl]propoxy}carbostyril. Melting point: 165°-166° C.
