The present invention addresses the problem of providing expandable methyl methacrylate-based resin particles that can provide expanded particles having an excellent mold-filling behavior and that can provide foam molded articles that exhibit excellent surface aesthetics. Provided are expandable methyl methacrylate-based resin particles that comprise a blowing agent and a base resin comprising the methyl methacrylate unit and an acrylate ester unit as constituent units, and that have a volume-average particle diameter of 0.30-0.50 mm and a particle size distribution (UT) of not more than 2.30.