Equalization of a temperature distribution in a flow direction on a cooling plate 15A is facilitated so that temperatures of plural cells 10 that thermally contact with the cooling plate 15A are equalized, to reduce variability in the state of charge-discharge and the lifetimes of the respective cells 10. A battery module 1 includes a cooling plate 15A having a refrigerant channel 14 in which a refrigerant circulates, and plural cells 10 that are thermally conductively coupled onto a surface of the cooling plate 15A, in which the refrigerant channel 14 is formed with plural large diameter pipes 201A that decelerate the refrigerant, and plural small diameter pipes 202A that accelerate the refrigerant, a channel sectional area of the large diameter pipes 201A is larger than a refrigerant channel sectional area of the small diameter pipes 202A arranged on an inflow side of the large diameter pipes 201A, and a channel sectional area of the small diameter pipes 202A is smaller than a refrigerant channel sectional area of the large diameter pipes 201A arranged on the inflow side of the small diameter pipes 202A.