The present invention provides an anode body for capacitors, which is formed of a sintered body that is obtained by sintering a powder mixture of a tungsten powder and a tungsten trioxide powder, and wherein the ratio of the tungsten trioxide powder to the total amount of the tungsten powder and the tungsten trioxide powder is 1 to 13 mass%. The present invention is able to reduce the number of semiconductor layer formation wherein polymerization of a semiconductor precursor is carried out a plurality of times on a dielectric layer. Consequently, a solid electrolytic capacitor element, in which a semiconductor layer that is composed of a conductive polymer is formed on a dielectric layer that is formed on the outer surface layer and the inner surface layer of the fine pores of a tungsten sintered body, can be produced efficiently.