The present invention provides porous resin particles made of a polymer of a monomer mixture, wherein the monomer mixture contains, as monomers, at least methyl methacrylate and a (meth)acrylic-based cross-linkable monomer, a content of the methyl methacrylate in the monomer mixture is 1 to 50% by weight, a content of the (meth)acrylic-based cross-linkable monomer in the monomer mixture is 50 to 99% by weight, the porous resin particles have a specific surface area of 130 to 180 m2/g, a pore volume of 0.3 to 0.7 ml/g, and an average pore size of 13 to 16 nm, an amount of unreacted methyl methacrylate remaining in the porous resin particles is 20 ppm or less, and the porous resin particles have a thermal decomposition starting temperature of 260° C. or more.