An object of the present invention is to provide compounds having read-through activity for use in treatment methods of genetic diseases caused by nonsense mutation, to provide pharmaceutical compositions comprising the compound, and to provide a treatment method of genetic diseases caused by nonsense mutation comprising administering the compound. The present invention can provide a method of producing wild type normal protein in a living body of a mammal from a gene with a premature termination codon being generated by a mutation, wherein the method comprises administering a compound expressed by the following formula (VI): ##STR00001## (wherein R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5 and X.sup.1 in the formula are as defined in description) or the like to the mammal.