Abstract: The present invention has its object to provide a resin composition excellent in mechanical strength and elasticity and further showing only a slight extent of gravity deformation under high temperature conditions. The invention relates to a resin composition which comprises an isobutylene-based polymer (A), an aromatic vinyl-based thermoplastic elastomer (B) comprising a polymer block (b1) the constituent monomer(s) of which is(are) an aromatic vinyl compound(s) and a polymer block (b2) the constituent monomer(s) of which is(are) an aliphatic hydrocarbon compound(s) other than isobutylene, and a filler (C). This composition can be suitably used as, for example, a sealant, in particular as a hot melt sealant for double glazing units, and as a hot melt spacer material for double glazing units.