A one-component epoxy resin composition characterized by containing an epoxy resin having two or more epoxy groups in its molecule (component (1)), a polythiol compound having two or more thiol groups in its molecule (component (2)), a compound that releases a basic component at curing temperatures and is soluble in the component (2) (component (3)) and a compound having Lewis acidity (component (4)). This is a reproducible practicable one-component epoxy resin composition that is a homogeneous mixture of epoxy resin and curing agent, having a strikingly improved satisfactory storage stability and exhibits excellent curability. By virtue of this composition, there can be provided an excellent method of realizing impregnation bonding or thin-film hardening, and further provided a functional product. |