PURPOSE: To obtain a composite foam which is light and has impact absorbing capacity, by mixing inorganic hollow microspheres with a flexible foamable resin and foaming the latter.

CONSTITUTION: Inorganic microspheres are homogeneously mixed with a flexible foamable resin for forming a matrix. The flexible foamable in this mixture is foamed to form a matrix in which the microsheres are dispersed. Examples of said resin include polyurethane foam, polyethylene foam, polystyrene foam and polyvinyl chloride foam. Examples of said inorganic hollow microspheres include foamed glass beads, "Shirasu" balloons and pearlite. The obtained composite foam can absorb a small impact by deformation of itself and can absorb a large impact by energy absorption.