Abstract: A temperature adjustment device (100 and 100a) includes: an insulation layer (400) provided in contact with bottom parts of the plurality of batteries (Bt); and a flow passage forming member (110) that is located on a side opposite to the plurality of batteries with the insulation layer interposed therebetween, and forms a flow passage (112) of cooling medium. The flow passage includes a plurality of cooling flow passages (f1 to f10) that face the bottom surfaces of one or more different batteries of the plurality of batteries with the insulation layer interposed therebetween, a common inflow passage (112a) that is connected to the plurality of cooling flow passages and in which the cooling medium is flowed, and a common exhaust passage (112b) which collects and exhausts the cooling medium exhausted from the plurality of cooling flow passages.