A sealing material, which comprises a curing product of a composition comprising (A) an acrylic polymer having at least one alkenyl group capable of undergoing hydrosilylation reaction, (B) a hydrosilyl group-containing compound and (C) a hydrosilylation catalyst as essential components, is suitable for use as cam cover seals and oil pan seals for automobile engines, fuel cell cooling medium seals, automobile wire harnesses seals, HDD cover gasket or vibration-insulating HDD cover gasket seals, etc.