Into 100 ml of ethanol were added 2.7 g of 6-(3-ethoxycarbonylpropoxy)carbostyril, 0.5 g of sodium ethylate and 5 ml of N-(2-hydroxyethyl)cyclohexylamine and reacted in an autoclave under a pressure of 110 atomospher at 140°-150° C. for 6 hours. After the reaction was completed, the reaction mixture was cooled and was concentrated under a reduced pressure. The residue thus obtained was dissolved in 200 ml of chloroform and washed with 1% K2CO3 aqueous solution, a diluted hydrochloric acid and water in this order, then dried with anhydrous sodium sulfate. Then the solvent was removed by distillation and the residue thus obtained was purified by a silica-gel column chromatography [the silica-gel used as Wako C-200, and the solvent used was a mixture of chloroform:methanol=20:1 (V/V)]. The crude crystals thus obtained was recrystallized from chloroform-petroleum ether to obtain 0.9 g of 6-{3-[N-(2-hydroxyethyl)-N-cyclohexylaminocarbonyl]propoxy}carbostyril as in the form colorless needle-like crystals. Melting point: 165°-166° C.
