An electrode of an embodiment includes a base material, and a catalyst layer provided on the base material and having a porous structure. When a sum of heights of all peaks belonging to Ir oxide is I0, the height of a peak of IrO2 (110) is I1, and the height of a peak of IrO2 (211) is I2, a ratio of (I1+I2)/I0, which is a ratio of spectra obtained by X-ray diffraction measurements using Kα rays of Cu in the catalyst layer, is 50% or more and 100% or less in a range of a diffraction angle of 20 degrees or more and 70 degrees or less.