NOVELTY - Producing (M1) a catalyst (C1) supporting a metal or an alloy on a support in it, involves: independently controlling a first temperature of a first supercritical fluid containing a precursor of the metal or precursor of the alloy that is dissolved in a supercritical fluid; independently controlling a temperature of the support to be a second temperature higher than the temperature of the first supercritical fluid; and supplying the first supercritical fluid controlled to be the first temperature to the support, to cause the metal or the alloy to be supported on the support.    USE - For producing catalyst supporting a metal or an alloy on a support in it e.g. electrode catalyst for fuel cell (claimed).    ADVANTAGE - With the catalyst production method, the temperature of the metal or alloy precursor-dissolved first supercritical fluid and the temperature of the support are each independently controlled. The first supercritical fluid is directly supplied to the support, thus it is possible to continuously continue supplying the first supercritical fluid at a predetermined temperature to the support while keeping the temperature of the first supercritical fluid. The supercritical fluid and the support are each independently temperature-controlled, and the temperature-controlled supercritical fluid is directly supplied to the support, this provides a production method capable of promoting the adsorption of the metal precursor onto the support. The catalyst production method prevents uneven supporting of a metal or the like supported on a support during a supporting treatment for a short treatment time.    DETAILED DESCRIPTION - Producing (M1) a catalyst (C1) supporting a metal or an alloy on a support in it, involves: independently controlling a temperature of a first supercritical fluid to be first temperature, where the first supercritical fluid containing a precursor of the metal or precursor of the alloy that is dissolved in a supercritical fluid; independently controlling a temperature of the support to be a second temperature higher than the temperature of the first supercritical fluid; and supplying the first supercritical fluid controlled to be the first temperature to the support, to cause the metal or the alloy to be supported on the support. INDEPENDENT CLAIMS are included for the following:    (1) an electrode catalyst for fuel cell, is produced by the catalyst production method (M1); and    (2) an apparatus (100) for producing the catalyst (C1), comprising: one reaction vessel (1) including first temperature control unit for independently controlling first temperature of the first supercritical fluid containing precursor of the metal or alloy that are dissolved in the first supercritical fluid; a second temperature control unit for independently controlling the second temperature of the support higher than the first temperature of the first supercritical fluid; and a first transfer unit for supplying the first supercritical fluid controlled to be the first temperature to the support.    DESCRIPTION OF DRAWING(S) - The figure shows a cross-sectional schematic diagram of the catalyst production-apparatus.    Vessel (1)    Supply valve (2)    Circulation fan (5)    Rectifying plate (7)    Support sample (8)    Sample heater (10)    Catalyst production apparatus (100)