Disclosed is a thermosetting resin composition of excellent low-temperature curability comprising an oxetane compound and also disclosed is a cured article obtained therefrom. The thermosetting resin composition comprises an oxetane compound (A) containing two or more oxetane functional groups in the molecule represented by the following general formula (1) and a heteropolyacid (B) as essential components. A cured article obtained by heat curing of this composition shows excellent mechanical properties, electrical properties, adhesive properties, resistance to heat, moisture, and chemicals, and the like. In formula (1), R1 is a hydrogen atom, alkyl group of 1 to 6 carbon atoms, fluorine atom, fluoroalkyl group of 1 to 6 carbon atoms, allyl group, aryl group, aralkyl group, furyl group, or thienyl group.