To cool a secondary battery and prevent a fault caused by an expansion of the secondary battery.

A cooling plate includes a first flat plate 6 and a second flat plate 7 having flexibility, an intermediate resin part 8, and a passage 10. The second flat plate 7 faces the first flat plate 6 with a predetermined space therebetween. The intermediate resin part 8 is interposed between the first flat plate 6 and the second flat plate 7, and elastically deforms according to the expansion of the secondary battery 2. The passage 10 is formed between the first flat plate 6 and the second flat plate 7, and a coolant in a form of gas or liquid passes through the passage 10.