To improve, for example, leakage current characteristics by providing an insulation plate with a specific thickness at the root of a lead wire for an anode.

A disc-shaped insulation plate 3 with a thickness T being larger than 0.2 mm and equal to or less than 0.5 mm is passed through a lead wire 2 for anode before being arranged at the root. Chip-type tantalum solid electrolytic capacitors 12 with a rating of 16 V and 100 μF is used. A sintered body is formed to a size of 1.97×3.37×3.0 mm by heating at a temperature of 1,400-1,600°C in vacuum after forming the pulverized powder of tantalum in a square shape. Also, a solid electrolyte layer 5 is made of a manganese dioxide layer. A graphite layer 6 and a silver layer 7 are successively formed on the manganese dioxide layer. Then, a lead wire 2 for anode has a diameter of 0.29 mm, a disc shaped insulation plate 3 made of Teflon with a thickness of 0.25 mm and an outer diameter of 1.5 mm is provided at the root, and at the same time an anode terminal is connected by resistance welding. An encapsulation is formed by performing the transfer molding of epoxy resin.