NOVELTY - Preparing an electrode catalyst, comprises: evaporating a platinum precursor and an organic precursor for formation of a carbon framework in their evaporators; supplying each of the evaporated platinum precursor and organic precursor to a reactor by carrier gas in a non-contact state; and heating the reactor, and then maintaining the reactor at a constant temperature to synthesize a platinum-carbon composite having a core-shell structure.    USE - The process is useful for preparing an electrode catalyst, which is useful for a fuel cell (claimed).    ADVANTAGE - The process: provides high performance, high durability electrode catalyst for a fuel cell, in large amount by one-step process using simultaneous evaporation process, thus reduces the production cost; provides electrode catalyst, in which a part or whole of the surface of platinum nanoparticles is surrounded by a carbon shell having a graphene structure, thus the electrode catalyst is not deactivated even when it is applied to an electrode reaction for a long period of time under severe conditions comprising high temperature, acidic and alkaline conditions; and utilizes platinum particles, which are not agglomerated, detached or corroded.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for:    (1) preparing a fuel cell electrode, comprising placing a support in a reactor, evaporating platinum precursor and an organic precursor for formation of a carbon framework in their evaporators, supplying each of the evaporated platinum precursor and organic precursor to the reactor, which has the support placed in it, by carrier gas in a non-contact state and heating the reactor and then maintaining the reactor at a constant temperature to synthesize a platinum-carbon composite supported on the support; and    (2) a fuel cell comprising an anode, a cathode and a polymer electrolyte, each of the anode and the cathode is composed of a support, a diffusion layer and a catalyst layer, which are sequentially stacked in that order, where the catalyst layer of at least one of the anode and the cathode is composed of the platinum-carbon composite having a core shell structure.