The present invention relates to a thermal management system including: a refrigerant circulation line including a refrigerant circulator, a first heat exchanger, a first expander and a third heat exchanger, wherein refrigerant circulates in the refrigerant circulation line; a heating line for heating the interior by circulating cooling water exchanging heat with the refrigerant through the first heat exchanger; and a cooling line for cooling heating sources by exchanging heat between the cooling water and air or exchanging heat between the cooling water and the refrigerant.