The present invention provides a capacitor wherein increase in the ESR value after a high temperature loading test is mitigated.A capacitor element, comprising an electric conductor having formed on the surface thereof a dielectric layer as one electrode, and a semiconductor layer, carbon layer and electrode layer formed sequentially on the dielectric layer, which capacitor element is characterized in that the carbon layer contains a dopant; a carbon paste as a material of the capacitor element; a capacitor using the capacitor element; and an electronic circuit and an electronic device using the capacitor.