A synthesis method of a metal catalyst having carbon shell, includes: a) forming a metal-ligand complex without further chemical additives by mixing a ligand with a metal precursor; b) separating the metal-ligand complex and collecting the separated metal-ligand complex; c) supporting the collected metal-ligand complex to a support by mixing the collected metal-ligand complex with the support in a solvent; and d) treating a composite consisting of the metal-ligand complex and the support by heating.