Provided are a conductive pattern manufacturing method and a conductive pattern formed substrate, capable of easily achieving a narrow pitch. A metal nanowire layer 12 is formed on the entirety of a part of at least one of the main faces of a substrate 10, pulsed light is irradiated thereto through a mask 14 provided with a light transmission portion 14a formed in a predetermined pattern, and the metal nanowires in the metal nanowire layer 12 at the region having the above predetermined pattern were sintered, to thereby obtain conductivity at the predetermined patterned region. Accordingly, a substrate provided with a conductive pattern having any selected pattern can be produced by simple steps.