Heat-expandable microspheres and applications thereof, the heat-expandable microspheres including a thermoplastic resin shell and a thermally-vaporizable blowing agent encapsulated therein. The thermoplastic resin is produced by polymerizing a polymerizable component containing (A) a nitrile monomer including methacrylonitrile, (B) a carboxyl-group-containing monomer and (C) a monomer having a functional group reactive with the carboxyl group. The polymerizable component satisfies the following conditions 1 and 2:
Condition 1: The weight fraction of the monomers (A), (B) and (C) in the polymerizable component satisfy the inequality shown below. Weight fraction of the monomer (C)