A resin composition for sealing a light-emitting device of the present invention includes a silsesquioxane resin including two or more oxetanyl groups, a cationic polymerization initiator and a metal oxide fine particle. Furthermore, a lamp of the present invention includes a package equipped with a sealing member, an electrode exposed in the bottom portion of the sealing member, and a light-emitting device arranged on the bottom portion and electrically connected with the electrode, wherein the light-emitting device is sealed with the resin composition for sealing a light-emitting device filled in the sealing member.