Provided is a drug sustained-release agent including a carbon material (porous carbon material) which has an inverse opal structure. The drug sustained-release agent includes a porous carbon material which has spherical pores having an average diameter of 1×10−9 to 1×10−5 m and arrayed three-dimensionally and which has a surface area of 3×102 m2/g. Or, the drug sustained-release agent includes a porous carbon material in which pores are arrayed in an arrangement corresponding to a crystal structure on a macroscopic basis. Or, the drug sustained-release agent includes a porous carbon material in which pores are arrayed at a surface thereof in an arrangement corresponding to the (111) plane orientation of a face-centered cubic structure on a macroscopic basis.