A vehicular heat management system includes a refrigerant circulation line configured to cool or heat a passenger compartment by generating a hot air or a cold air depending on a flow direction of a refrigerant, a cooling water circulation line configured to heat the passenger compartment with waste heat of an engine by allowing cooling water of the engine to circulate through a heater core, a refrigerant-cooling water heat exchanger disposed in the cooling water circulation line to allow the refrigerant and the cooling water to exchange heat, and an engine cooling water independent circulation unit configured to allow the cooling water passed through the engine to bypass the heater core and the refrigerant-cooling water heat exchanger.