There are provided a modified silicone compound prepared by reacting: (A) a siloxane diamine represented by the general formula (1); (B) a maleimide compound with at least two N-substituted maleimide groups in the molecular structure; and (C) an amine compound with an acidic substituent; and also provided a thermosetting resin composition, a prepreg, a laminated plate, and a printed wiring board that are formed by using this compound. The multi-layered printed wiring board produced by using the laminated plate formed by using the prepreg obtained from the modified silicone compound and the thermosetting resin composition of the present invention through laminate molding has an excellent glass transition temperature, coefficient of thermal expansion, copper foil adhesion, hygroscopicity, hygroscopic solder heat resistance, and copper-stuck solder heat resistance. Therefore, the multi-layered printed wiring board is useful as a highly integrated semiconductor package and a printed wiring board for an electronic device.