One embodiment of a temperature regulating device according to the present invention comprises: a first loop in which a refrigerant is circulated through a battery and a heater; a second loop in which the refrigerant is circulated through a heater core and the heater; a first bypass which bypasses the heater in the first loop; a third loop in which the refrigerant is circulated through the battery and the first bypass; and a mixing valve which is positioned at an intersection between the first loop and the first bypass. In a first mode, the refrigerant flowing in the second loop and the refrigerant flowing in the third loop circulate independently. In a second mode, refrigerant that has passed through the heater without passing through the first bypass is circulated in the first loop. In a third mode, the amount of the refrigerant flowing through the third loop via the first bypass without passing through the heater and the amount of the refrigerant flowing through the first loop while passing through the heater are adjusted by the mixing valve, and the refrigerant that has passed through the heater is circulated in the second loop.