The invention relates to a curable resin composition containing (A) a multifunctional benzoxazine compound having two or more benzoxazine rings, (B) an epoxy compound having at least one norbornane structure and at least two epoxy groups, (C) a biphenyl type epoxy compound, and (D) a curing agent, and optionally (E) an inorganic filler and (F) a curing accelerator; a cured product thereof; methods of producing the curable resin composition and the cured product; and a semiconductor device in which a semiconductor element is disposed in a cured product obtained by curing a curable resin composition containing components (A) to (D), and optionally components (E) and (F).