PURPOSE: To form a hollow part by a low-cost resin sealing operation only without putting a lid by a method wherein a hermetically sealed resin lid is molded by using a resin injected into a metal mold by leaving a space including a chip by the action of a centrifugal force generated when the metal mold is turned.
CONSTITUTION: A substrate 1 on which a chip 2 has been mounted is supported inside a cavity 14 formed by split metal molds 8. The substrate 1 in which an uneven part 1a has been formed on the surface at its whole circumference is used. The substrate 1 is supported; after that, a resin 4a before it is hardened is injected into the cavity 14 of the split metal molds 8. Before the resin is hardened, the split metal molds 8 are turned with an axial line X as the center. At this turning operation, the resin inside the cavity 14 flows along the inner surface of the metal molds by the action of a centrifugal force. A resin lid whose shape leaves a space including the chip 2 is molded; its whole circumference part is bonded and united to the uneven part 1a at the substrate 1. After the resin has been hardened, the split metal molds are removed. Thereby, a hollow part 7 can be formed by a low-cost resin sealing operation without putting a lid on the semiconductor chip 2.