To provide a carbon support for catalysts for fuel cells, which increases the power generation performance of fuel cells, a catalyst for fuel cells, a catalyst layer for fuel cells, and a method for producing the carbon support. A carbon support for catalysts for fuel cells, wherein the carbon support includes at least one pore; wherein a thickness of a carbon wall of the carbon support, which is derived from a three-dimensional pore structure of a silica mold obtained by pore volume measurement of the silica mold by nitrogen adsorption analysis, is 3.3 nm or more and 11.2 nm or less; and wherein a carbon wall content is more than 60.3 ml/g and less than 190.8 ml/g.