The objective of the present invention is to provides a cationically curable epoxy resin composition excellent in sealing and adhesive property specifically to glass, excellent reflow resistance property, moisture resistance and water resistance while keeping a good workability intrinsic to a light curable resins. The invention provides a cationically curable epoxy resin composition comprising: (a) an epoxy resin component; (b) a cationic photo-initiator; (c) a cationic thermal-initiator and (d) a filler selected from the group consisting of oxides, hydroxides and carbonates containing a Group II element in the long periodic table.