PURPOSE: To obtain the glaucoma-treating agent and the intraocular pressure- lowering agent each containing an aminoalkoxybibenzyl compound or its salt as an active ingredient, and useful for preventing and treating the glaucoma, hypertension, etc.

CONSTITUTION: The glaucoma-treating agent and the intraocular pressure- lowering agent each contains a compound of formula I [R1 is H, halogen, 1-5C alkoxy, 2-6C dialkylamino; R2 is H, halogen, 1-5C alkoxy; R3 is H, OH, -O-(CH2)n-COOH (n is 1-5),-O-CO-(CH2)l-COOH (l is 1-3); R4 is group of formula II (R5,R6 are H, 1-8C alkyl); m is 0-5] or its salt, e.g. (±)-1-[0-[2-(mmethoxyphenyl)ethyl)phenoxy]-3-(dimethylamino)-2-propyl hydrogen succinate hydrochloride, as an active ingredient. The dose of the compound of formula I is generally 0.5-50mg/kg body weight/day, usually 1-30mg/kg body weight/day, and is particularly effective for herpertensive glaucoma.