There are disclosed a foamable composition which comprises (A) a vinyl chloride resin, (B) an inorganic substance containing inorganic fibers of not less that 1 .mu.m diameter, (C) a solvent having properties such that when a mixture, which is composed of 100 parts by weight of a vinyl chloride resin of average polymerization degree of 2400, 100 parts by weight of the solvent, and 6 parts by weight of dibasic lead stearate, is kneaded using a plastograph at 30 rpm while raising the temperature it exhibits a maximum torque of 4 to 25 N.m on the kneader, and (D) a decomposition-type blowing agent; and a process for preparing such; a rigid, foamed article made therefrom; and a process for preparing such article. Since the rigid, foamed article of the invention does not contain asbestos, it is not injurious to human safety and health. It has very low amounts of emitted heat, smoke, and noxious gas on burning; is deformed only a very small amount on burning; is excellent in dimensional stability and heat resistance in use at high temperatures; causes little turning to white ash even on forced burning, and is of low cost.