A method for bonding metallic plates includes: sandwiching a laminated body, which includes a plurality of metallic plates and is formed with an inner cavity opening on a surface thereof, between a pair of jigs each having a flat abutment surface abutting against respective surfaces of the laminated body, wherein at least one of the jigs is formed with an atmosphere communication path, which communicates with the inner cavity and atmosphere; and heating the laminated body while applying pressure to the laminated body with the pair of jigs in a lamination direction of the laminated body.