A filling method of conductive paste includes a step of providing a protective film on a principal surface of a metal foil clad laminated sheet, a step of forming bottomed via holes, a step of from a surface to a midway thereof to forma conductive paste flowing groove having the via holes, a step of disposing a housing member on the film, and thereby, causing conductive paste injecting channel and a vacuum evacuating channel to communicate with a conductive paste flowing space S, a step of depressurizing the space S via the channel, and a step of injecting conductive paste into the space S via the channel, and thereby, filling an inside of the via holes with the conductive paste.