A composite material according to the present invention includes a solid portion including inorganic particles and a resin. The composite material has a porous structure including a plurality of voids surrounded by the solid portion. In the composite material, a ratio of a smallest heat conductivity of heat conductivities λx, λy, and λz respectively in x-axis, y-axis, and z-axis directions perpendicular to each other to a largest heat conductivity of the heat conductivities λx, λy, and λz is 0.8 or more.