Provided is a resin composition for ink jet, including at least a component (A) and a component (B), in which the component (A) includes a (b)-(a)-(b) type isobutylene-based triblock copolymer composed of an isobutylene-based polymer block (a) and a styrene-based polymer block (b), and the component (B) includes a cyclic-polyolefin-based polymer. The resin composition for ink jet has water-vapor barrier properties and gas barrier properties comparable to or more than those of crosslinked rubbers having high water-vapor barrier properties and high gas barrier properties, and can be molded by any of press-molding, injection molding, extrusion molding, and the like.