To impart high fluidity to a curable resin composition for capable of continuing stable manufacturing without causing any unfilled part or weld in transfer molding using the thermosetting resin composition.

A thermosetting resin composition is obtained by keeping a thermosetting resin composition, which is prepared by pre-kneading a component consisting of a resin and a filler, in a condition of 25±5°C for 120 hours, and subsequently performing post-kneading. In the obtained thermosetting resin composition, a spiral flow length (based on the electric functional material industry standard T901 and measured at a mold temperature 170°C, a transfer pressure 7 Mpa, and a curing rate 120 sec) is ≥15% in terms of an elongation percentage relative to that of a thermosetting resin composition obtained by batch kneading without performing separate pre-kneading and post-kneading.