A laminate cased battery in which at least one of curvature radiuses RB and RD of the corners (bottom side corners) where the first side surface respectively meets the second main surface, the third side surface and the fourth side surface is set to be larger than at least one of curvature radiuses RA and RC of the corners (top side corners) where the second side surface respectively meets the second main surface, the third side surface and the fourth side surface.