According to one embodiment, a constraint jig, used in manufacturing of a battery in which an electrode group is stored in an exterior container having a square shape, is provided. The constraint jig includes a plurality of metal constraint plates. The plurality of constraint plates are arrayed, and form a space in which the battery is arranged between constraint plates adjacent to each other. The plurality of constraint plates constrain the battery arranged in the space, and thus prevent an expansion of the exterior container beyond a predetermined range. Each of the constraint plates has an inner hollow, and includes an inflow port allowing a cooling fluid to flow into the inner hollow and an outflow port allowing the cooling fluid to flow out of the inner hollow.