A benzothiophene oxide derivative represented by the following general formula or a salt thereof: ** Formula ** wherein, R1 and R2 are the same or different and represent one or more groups selected from a hydrogen atom, a halogen atom , an alkyl, aryl, aralkyl, alkoxy, aryloxy, alkylthio, arylthio, alkenyl, alkenyloxy, amino, alkylsulfonyl, arylsulfonyl, carbamoyl or a heterocyclic group which may be substituted, an amino, hydroxyl or carboxyl group which may be protected, nitro group and an oxo group； R3 represents an alkylamino group that may be substituted, an amino or hydroxyl group that may be protected； and m and n are the same or different and each represent an integer from 1 to 6； wherein, a substituent for the alkyl group, the aryl group, the aralkyl group, the alkoxy group, the aryloxy group, alkylthio group, the arylthio group, the alkenyl group, the alkenyloxy group, the amino group, the alkylsulfonyl group, the arylsulfonyl group, carbamoyl group and heterocyclic group in R1 and R2 and a substituent for alkylamino group in R3 are a group selected from a halogen atom, a linear or branched C1-C6 alkyl group, a cycloalkyl group, an aryl group , a linear or branched C1-C6 alkoxy group, an aryloxy group, an alkyl (C1-C6) thio group, an arylthio group, a C2-C6 alkenyl group, an alkyl (C1-C6) sulfonyl group, an arylsulfonyl group, an alkylamino group, an amino group that can be protected, a hydroxyl group that can be protected, a carboxyl group that can be protected, an acyl group and a heterocyclic group； amino protecting groups are an acyl group, an alkyloxycarbonyl group, an aralkyloxycarbonyl group, an aryloxycarbonyl group, an aralkyl group, an alkoxyalkyl group, an aralkyloxyalkyl group, an arylthio group, an alkylsulfonyl group, an arylsulfonyl group, a trimethylsilyl group, a trimethylsilyl group, a triethylsilyl group and a tributyl silyl group； the hydroxyl protecting groups are an acyl group, an alkyloxycarbonyl group, an aralkyloxycarbonyl group,
