A partition plate for an intake port of a cylinder head to be manufactured by cast molding is preliminarily set prior to the cast molding in a sand core applied to form the intake port and then cast in by the cast molding to partition the intake port into a plurality of ports. The partition plate is provided with an intake-side distal end, a cylinder-side distal end, a pair of side edges continuous with the intake-side distal end and the cylinder-sided distal end and to be cast in by molten metal during the cast molding. Each of the pair of side edges having end faces facing in a thickness direction and a side end face continuous with the end faces. The partition plate is further provided with a promoter section provided on at least one of the side end face and the end faces of each of the pair of side edges to promote solidification of the molten metal.