To provide a partitioning plate for heat dissipation of a battery case which has superior oxidation resistance and alkaline corrosion resistance in addition to heat dissipation characteristic.

In the battery case in which a plurality of unit batteries are laminated and stored, the partitioning plate 1 for heat dissipation in which neighboring unit batteries are sectioned is composed of aluminum base material having a surface treatment film, has a thickness of (mm) along the lamination direction of the unit battery and a length of L (mm) along the direction perpendicular to the lamination direction, and equipped with one or more ventilation holes D penetrating along the longitudinal direction. If the maximum width of the ventilation hole in the lamination direction is F (mm) and the cross-sectional area of the ventilation hole in the lamination direction is S (mm2), then F/0.6 and 3L/S45 are satisfied in the partitioning plate for heat dissipation.