A capacitor built-in substrate of the present invention includes; a base resin layer; a plurality of capacitors arranged side by side in a lateral direction in a state that the capacitors are passed through the base resin layer, each of the capacitors constructed by a first electrode provided to pass through the base resin layer and having projection portions projected from both surface sides of the base resin layer respectively such that the projection portion on one surface side of the base resin layer serves as a connection portion, a dielectric layer for covering the projection portion of the first electrode on other surface side of the base resin layer, and a second electrode for covering the dielectric layer; a through electrode provided to pass through the base resin layer and having projection portions projected from both surface sides of the base resin layer respectively; and a built-up wiring formed on the other surface side of the base resin layer and connected to the second electrodes of the capacitors and one end side of the through electrode.