A vehicular heat management system includes a refrigerant circulation line configured to generate hot energy or cold energy depending on a flow direction of a refrigerant, a heater core side coolant circulation line configured to transfer refrigerant heat generated in the refrigerant circulation line to a heater core to heat a passenger compartment, and a battery side coolant circulation line configured to receive coolant heat of the heater core side coolant circulation line via a coolant and then circulate the coolant through a battery to preheat the battery.