A chip solid electrolyte capacitor with low ESR and small initial failure ratio comprising a plurality of solid electrolyte capacitor elements each produced by stacking a dielectric oxide film layer, a semiconductor layer and an electrically conducting layer in this order to form a cathode part on a surface of an anode substrate exclusive of the anode part at one end, the anode substrate comprising a sintered body of a valve-acting metal or an electrically conducting oxide or comprising the sintered body connected with a metal wire, which is a chip solid electrolyte capacitor obtained by horizontally laying the plurality of electrolyte capacitor elements in parallel with no space on a pair of oppositely disposed end parts of a lead frame such that the anode part or the metal wire and the cathode part come into contact with the lead frame, joining each element, and molding the entire with a resin while leaving outside the external terminal parts of the lead frame, wherein the volume ratio of one sintered body exclusive of the anode part to the chip volume is from 0.042 to 0.110; and an electronic instrument using the chip solid electrolyte capacitor.