Heat-expandable microspheres having an almost spherical shape and high expansion performance and exhibiting good workability when mixed with a resin, a process for producing the heat-expandable microspheres, and applications thereof. The heat-expandable microspheres include a thermoplastic resin shell and a blowing agent encapsulated therein and vaporizable by heating. The thermoplastic resin is produced by polymerizing a polymerizable component containing a methacrylate monomer and a carboxyl-containing monomer, and optionally containing a nitrile monomer in an amount ranging from 0 to 30 parts by weight to 100 parts by weight of the total amount of the methacrylate monomer and the carboxyl-containing monomer. The blowing agent contains a hydrocarbon having at least 8 carbon atoms per molecule.