<;P>;PROBLEM TO BE SOLVED: To provide an anticancer agent effective for lung cancer. <;P>;SOLUTION: This anticancer agent contains, as an active ingredient, a substance which binds to HB-EGF to inhibit the bonding of the HB-EGF to an EGF receptor, wherein a cancer of the treatment target is Gefitinib-sensitive and/or Gefitinib-resistant lung cancer. <;P>;COPYRIGHT: (C)2009,JPO&INPIT