Abstract: According to the present invention, there is provided expandable beads of a styrene-modified linear low-density polyethylene-based resin comprising a volatile blowing agent and a base resin, the base resin containing more than 300 parts by weight and less than 1000 parts by weight of a polystyrene-based resin component relative to 100 parts by weight of a non-crosslinked linear low-density polyethylene-based resin component, wherein the base resin contains 2 to 40 wt % of a gel component comprising a graft copolymer of the polystyrene-based resin component and the low-density polyethylene-based resin component.