An electrode catalyst, including: a metal compound which contains an oxygen atom and at least one metal element selected from a group consisting of Group 4 elements and Group 5 elements in the long-form periodic table, and a carbonaceous material which covers at least part of the metal compound; wherein an oxygen deficiency index, which is represented as an inverse number of a peak value of a first nearest neighbor element in a radial distribution function obtained by Fourier-transforming an EXAFS oscillation in EXAFS measurement of the metal element, is 0.125 to 0.170; and a crystallinity index, which is represented as a peak value of a second nearest neighbor element in the radial distribution function, is 4.5 to 8.0.