Novel N3S1 chelator-folate derivatives, a preparation method thereof, and a composition for diagnosis and treatment of tumor including the same as an active ingredient are provided. The novel N3S1 chelator-folate derivatives or a pharmaceutically acceptable salt thereof are easily introduced into the cells using receptor binding to tumor expressing α-folate receptor (α-FR). Accordingly, the folate derivatives, labeled with radioisotope such as technetium, or rhenium, can be advantageously used for the diagnosis and treatment of tumor using tumor imaging and irradiation from the isotope, and therefore, can be widely used for the purpose of labeling a variety of radiopharmaceuticals.