A process of a porous body comprises the steps of disposing a first material in which pores are formed by anodization on a substrate to form a first layer, disposing on the first layer a second material which has a hardness lower than that of the first material and an oxide of which is dissolved by an anodization step to form a second layer, forming a concave structure on a surface of the second layer, oxidizing the second layer, and subjecting the first layer to anodization to dissolve the second layer.A magnetic recording medium or a light-emitting element comprises a first layer which is comprised of an oxide of aluminum and comprises a porous portion on a substrate, and a second layer on the first layer which has a hardness lower than that of the first layer and is comprised of a metal element, wherein the pores are packed with a magnetic substance or a light-emitting material.