It is an object of the present invention to provide a production process which can produce a fuel cell catalyst having excellent durability and high oxygen reducing activity.The process for producing a fuel cell catalyst including a metal-containing oxycarbonitride of the present invention includes a grinding step for grinding the oxycarbonitride using a ball mill, wherein the metal-containing oxycarbonitride is represented by a specific compositional formula; balls in the ball mill have a diameter of 0.1 to 1.0 mm; the grinding time using the ball mill is 1 to 45 minutes; the rotating centrifugal acceleration in grinding using the ball mill is 2 to 20 G; the grinding using the ball mill is carried out in such a state that the metal-containing oxycarbonitride is mixed with a solvent containing no oxygen atom in the molecule; and when the ball mill is a planetary ball mill, the orbital centrifugal acceleration mill is 5 to 50 G.