A production method of a wired circuit board can prevent corrosion of a first
thin
metal film inwardly of a conductor layer, due to the forming of an undercut portion
caused by a skirt portion of a plating resist. A first thin metal film is formed
on an insulating base layer. A plating resist is formed in a reversal pattern to
a wiring circuit pattern on the first thin metal film, and a conductor layer is
formed in the wiring circuit pattern on the first thin metal film exposed from
the plating resist. Thereafter, the plating resist is removed and, then, a second
thin metal film is formed on the conductor layer and first thin metal film. Thereafter,
the second thin metal film and then all portions of the first thin metal layer,
except portions thereof where the conductor layer is formed, are removed.