Disclosed is a protein kinase C enhancer characterized by containing a benzothiophenealkylether derivative represented by the general formula below or a salt thereof. (formula) (In the formula, R and R may be the sameor different and represent one or more groups selected from a hydrogen atom, ahalogen atom, an alkyl group, an aryl group, an aralkyl group, an alkoxy group,an aryloxy group, an alkenyl group, an amino group, a heterocyclic group, an optionallyprotected amino group, a hydroxyl group, an carboxyl group, an oxo group and thelike； R represents an alkylamino group, an amino group, a hydroxylgroup or the like； and m and n may be the same or different and represent an integerof 1-6.) This protein kinase C enhancer is useful for treatment or preventionof various diseases associated with protein kinase C.
