PURPOSE: A resin composition excellent in moisture resistance, rust inhibition and adhesion, prepared by adding a curing agent and a specified additive to an epoxy resin.

CONSTITUTION: The titled composition prepared by adding an additive comprising a curing agent (e.g., phenolic resin), an oxidized wax (e.g., oxidized paraffin wax) or its derivative (e.g., oxidized wax methyl ester), and an organotitanium compound (e.g., isopropyl tristearyl titanate) to an epoxy resin. In said mixing 0.1W10pts.wt. oxidized wax (derivative) and 0.01W5pts.wt. organotitanium compound are used per 100pts.wt. epoxy resin. When this composition is used as, e.g., a sealing resin for semiconductor devices or other electronic circuit parts, it can form a film excellent in moisture resistance, rust inhibition and adhesion because the above additive intervenes between this composition and the sealed object to prevent external moisture and ionic impurities from penetrating to the surface of the object.