The present invention sufficiently secures conductor component content ratio in wiring formed on a multilayer circuit board and increases reliability by fabricating the multilayer circuit board by steps of drawing wiring precursor patterns containing a paste of compound for forming wiring conductor containing (a) superfine metal particles (metal nanoparticles) whose average particle size is 1-10 nm; (b) an organic coating compound coated on the surface of the superfine metal particle in the film thickness of 1-10 nm; (c) a latent reactive organic compound reacting with the organic coating compound in the range of 100-250.degree. C., (d) metal particles whose average particle size is 0.5-10 .mu.m, and (e) dispersion medium that stably disperses components (a) through (d) on a substrate by screen printing, sintering by heating the patterns to 100-250.degree. C., and electrochemically treating the patterns to allow the conductor to deposit in a desired cross-sectional area in the inside.