Electrode foil for electrolytic capacitor, electrolytic capacitor, and production methods therefor

An electrode foil for an electrolytic capacitor includes a metal foil having a porous part, and a dielectric layer covering a surface of a metal framework constituting the porous part. The dielectric layer includes a first layer containing an oxide of a second metal different from a first metal contained in the metal framework. The first layer has a thickness T1. The first layer contains at least one kind of additive element selected from the group consisting of carbon, phosphorus, boron, and nitrogen. The first layer includes a first region from an outer surface of the first layer to a center of the first layer in a thickness direction, and a second region from the center to an inner surface of the first layer. A content of the at least one kind of additive element in the first region is greater than a content of the at least one kind of additive element in the second region.