A thermally expandable vinyl chloride resin composition is provided. It includes (A) 100 parts by mass of a vinyl chloride resin, (B) 5 to 200 parts by mass of an inorganic filler, (C) 10 to 300 parts by mass of a thermally expandable graphite, (D) 0.1 to 10 parts by mass of a fluororesin, and (E) 10 to 300 parts by mass of a phosphorus compound. The composition exhibits favorable thermal expansion properties and favorable shape retention following thermal expansion upon exposure to high temperatures.