An excellent medicine for the treatment or prevention of hypertension or the like is provided. A specific acid addition salt of (R)-2-amino-1,4-dihydro-6-methyl-4-(3-nitrophenyl)-3,5- pyridinedicarboxylic acid 3-(1-diphenylmethylazetidin-3- yl)ester 5-isopropyl ester is useful as a medicine for the treatment or prevention of hypertension or the like.