The present invention relates to a tumor tissue-penetrating peptide specifically binding to neuropilin, or a fusion protein, a small molecule drug, a nanoparticle, or a liposome having the peptide fused therein. In addition, the present invention relates to a method for preparing the same and a pharmaceutical composition comprising the same for treating, diagnosing, or preventing cancer or angiogenesis-related diseases. The fusion antibody in which a tumor tissue-penetrating peptide according to the present invention is fused to the C-terminus of an anticancer antibody heavy-chain constant region (Fc) achieves the property of specifically binding to neuropilin, and thereby, specifically accumulates in tumor tissue, widens intercellular gaps between tumor vascular endothelial cells, promotes extravasation, increases infiltration within tumor tissue, and thus, shows a remarkably increased in vivo tumor-suppressing activity. Furthermore, the fusion protein having a tumor tissue-penetrating peptide according to the present invention fused therein inhibits the angiogenic function among the functions of neuropilin coreceptors resulting from targeting of neuropilin, and is therefore expected to have an alleviating effect on angiogenesis-related diseases.
