This invention provides a catalyst for a fuel cell electrode, a process for producing a catalyst for a fuel cell electrode, a membrane electrode assembly, and a fuel cell, which are advantageous in suppressing aggregation of a carbon support such as carbon nanotubes, and in closely contacting the three of the carbon support, a catalyst component and an electrolyte component with each other. A catalyst for a fuel cell electrode contains a carbon support (e.g., CNTs) having a pi-conjugated system, an electrolyte component having an aromatic ring, and a catalyst component. A process for producing a catalyst for a fuel cell electrode. By contacting, in a solvent, a carbon support (e.g., CNTs) having a pi-conjugated system, an electrolyte component having an aromatic ring, and a catalyst component with each other, the carbon support can be modified with the electrolyte component and loaded with the catalyst component.