A sesquiterpene derivative expressed by the general formula (I): ##STR1## wherein R.sup.1 represents a hydrogen atom, a lower alkyl group or a lower alkanoyl group; R.sup.2 and R.sup.3, which may be the same or different, each represents a formyl group, a hydroxymethyl group, a hydroxyl group, a carboxyl group, a lower alkanoyloxymethyl group, or a group of the formula --CH.dbd.CR.sup.7 R.sup.8, wherein R.sup.7 and R.sup.8, which may be the same or different, each represents a hydrogen atom, a cyano group, a lower alkoxycarbonyl group or a carboxyl group, or R.sup.2 and R.sup.3 may combine to form a lactone ring of the formula ##STR2## in which R.sup.9 represents a hydrogen atom or a hydroxyl group; R.sup.4 and R.sup.6, which may be the same or different, each represents a hydroxyl group or a lower alkanoyloxy group; R.sup.5 represents a hydrogen atom; R.sup.4 and R.sup.5 may together form an oxo group (.dbd.O); and R.sup.4 and R.sup.6 may combine to form a lower alkylidenedioxy group, the pharmaceutically acceptable salts thereof, processes for the production of the compounds of the general formula (I) and the salts thereof, pharmaceutical composition containing the compounds of the general formula (I) and the salts thereof, and method of use of the compounds of the general formula (I) and the salts thereof.