To provide a composition for a heat storage material capable of forming a heat storage material having no phase separation and no bleeding of a liquid phase at over a maximum crystal transition temperature of a heat storage substance as a component, excellent in shape retention property and further excellent in flowability during molding.

The composition for a heat storage material contains a hydrogenated conjugated diene copolymer which is a hydrogenated material of a block copolymer represented by the general formula [A-B-A]n or (A-B)x-Y, where A represents a polymer block (A) containing a constitutional unit derived from an alkenyl aromatic compound of over 50 mass%, B represents a polymer block (B) containing a constitutional unit derived from a conjugated diene compound of over 50 mass% and having the vinyl bond content of 30 mol% or more, n represents an integer of 1 to 3, x represents an integer of 2 or more and Y represents a coupling agent residue respectively, and having a ratio in terms of mass between the copolymer block (A) and the copolymer block (B) ((A)/(B)) of 1/99 to 5/95, and has a weight average molecular weight in terms of polystylene of 300,000 or more, and the heat storage substance.