Catalyst electrode, and electrochemical device

Disclosed is a catalyst powder (1) contained in an electrode, wherein the catalyst powder includes a catalytic substance (3) supported on a conductive powder (2), the catalytic substance being comprised of at least a catalyst, the weight ratio of the catalytic substance to the catalyst powder is in the range of 55 to 75 wt%, and the areal density of the catalytic substance is in the range of 1 to 3 mg/cm 2 . Also disclosed is a catalyst electrode including the catalyst powder and a solid polymer electrolyte. Further disclosed is an electrochemical device including a plurality of electrodes, and an ionic conductor sandwiched between the electrodes, wherein the above-mentioned catalyst electrode constitutes at least one of the plurality of electrodes.