To stably remove a resin body formed in a supply route of a resin in a sealing step. A leadframe has, in a sub-runner portion thereof, a sub-through-hole. The sub-through-hole has, along a first direction along which the sub-runner portion extends, a first portion located on the side of a main-runner portion and a second portion located on the side of a gate portion relative to the first portion. In a plan view, an opening width of the sub-through-hole in the first direction is greater than that of the sub-through-hole in a second direction perpendicular to the first direction. In a plan view, an opening width of the sub-through-hole in the second direction gradually decreases from the first portion to an end portion of the second portion on the side of the gate portion.