It has been found out that among antibodies showing reactivity with wild type TGF-α, antibodies less reactive with G79A-substituted TGF-α have an excellent growth-suppressing effect on cancer cells having a mutated Ras gene. Further, it has been found out that most of these antibodies have an activity of inhibiting EGFR tyrosine phosphorylation and/or an induction-suppressing activity on vascular endothelial cells.