A catalyst electrode is constituted by a catalyst material and a porous carbon frame for carrying the catalyst material. The catalyst material has a structure comprising whiskers or a structure comprising flaky parts. The porous carbon frame has pores having a pore diameter of 0.5 μm or more and 10 μm or less in terms of a mode diameter and has a porosity, in the catalyst electrode, in a range of from 12% to 80%.