The present invention relates to a novel a-Naphthylurea derivative. This substance can remarkably depress phosphorylation of VEGFR2 and PDGFR-β receptor protein tyrosine kinases at the level of nanomolar concentration, and is a novel protein tyrosine kinase depressor, which can be used to cure a disease or symptom induced by the protein tyrosine kinase, such as a malignant tumor or an eye disease accompanied by pathological new vessels.