To provide new sulfonamide derivatives having an excellent antitumor activity and only a low toxicity and a process for producing them. Sulfonamide derivatives of the general formula (I): wherein preferably R<1> represents a lower alkoxy group, R<2>, R<3>, R<4>, R<5>, R<6> and R<7> may be the same or different from one another and each represent a hydrogen atom, halogen atom or lower alkyl group, A and B may be the same or different from each other and each represent =N- or =CH-, E represents an aromatic 6-membered cyclic group (which may have 1 or 2 nitrogen atoms in the ring) which may be substituted with 1 to 3 substituents which may be the same or different from one another with the proviso that a combination of R<1> which is a hydrogen atom, lower alkyl group, nitro group or amino group which may be protected, R<2> and R<3> which are each a hydrogen atom, A and B which are each =CH- and E which is a phenyl group which may be substituted with 1 to 3 substituents G which may be the same or different from one another is excluded, or pharmacologically acceptance salts of them.