A specific targeting peptide binding to glypican-3 can specifically binds to glypican-3 overexpressed in carcinoma cells and includes an amino acid sequence represented by SEQ ID NO:1 or some thereof. Glypican-3 is overexpressed in malignant tumors including hepatocellular carcinoma, melanoma, germ cell tumor, etc., and may be targeted in diagnosis and treatment of tumors by labeling the targeting peptide. A diagnosis using the specific peptide may detect even small tumors more accurately than conventional methods. A treatment method using the specific peptide may remove only carcinoma cells without harming other normal tissues.