A method of producing a structure having narrow pores includes a first step of bringing pore-guiding members into contact with upper and lower surfaces of a member comprising aluminum as a principal ingredient and a second step of anodizing the member comprising aluminum as the principal ingredient to form narrow pores. The pore-guiding members contain the same material as a principal ingredient. The second step includes preferably a step of transforming the member comprising aluminum as the principal ingredient into a porous body comprising alumina having narrow pores oriented substantially parallel to the interfaces between the pore-guiding members and the member comprising aluminum as the principal ingredient.