Abstract: A battery temperature regulation device includes: fill port provided in a circuit in which coolant circulates; a pump; a plurality of heat exchangers; a solenoid valve arranged in a branching path of the circuit and switching the flow path; a controller controlling switching of the flow path; a heat exchange circuit performing heat exchange with the battery; a first circuit; and a second circuit, the fill port is arranged in either of the first and second circuit, and when filling coolant from the fill port, by performing open/close control of the solenoid valve after operation of the pump, and switching the circuit to the fill port arrangement circuit in which the fill port is arranged, air remaining in the circuit is discharged from the fill port.