PURPOSE: To measure the heat conductive state of a thermosetting resin, by mixing pigment showing discoloration only in one direction transferred to high temp. from low temp. in the thermoplastic resin and, after thermal molding, the discoloration state of the molded thermosetting resin is detected.

CONSTITUTION: A plurality of plunger pots 2 and a plurality of cavities 3 corresponding to each pot 2 are provided to a mold 1 and a thermosetting resin softened by the heat imparted to the mold 1 from the outside is received in each pot 2. A semiconductive chip device such as an integrated circuit is arranged to each cavity 3. Each pot 2 and a plurality of the cavities 3 are connected to a runners 4 and the resin softened by a preheater in each pot 2 is sent into the gate of each cavity 3 by the plunger 5 provided in the pot 2 to perform thermal molding. Heat-sensitive pigment showing discoloration only in one direction transferred to high temp. from low temp. is mixed in the thermosetting resin within each pot 2.