The imidazole derivatives of the general formula: ##STR1## wherein R.sup.1 represents a hydrogen atom, or a straight- or branched-chain alkyl group containing from 1 to 12 carbon atoms, R.sup.2 represents a hydrogen atom, or a straight- or branched-chain alkyl group containing from 1 to 4 carbon atoms, R.sup.3 represents a straight- or branched-chain alkyl group containing from 1 to 10 carbon atoms, and m and n, which may be the same or different, each represent zero, or an integer of 1 to 10, and non-toxic acid addition salts thereof, and, when R.sup.1 represents a hydrogen atom, non-toxic salts thereof, are new compounds. These compounds have a strong inhibitory effect on thromboxane synthetase from rabbit platelet microsomes, and are useful as therapeutically active agents for inflammation, hypertension, thrombus, cerebral apoplexy and asthma.