Disclosed are: a microetching agent which can form roughened shapes less affected by differences in the crystallinity of the copper and with which roughened shape excellent in terms of adhesiveness to resins, etc. can be formed on either electrolytic copper or rolled copper; and a method for producing a wiring board which includes a step of roughening a copper surface using the microetching agent. In the present invention, the microetching agent for copper is an acidic aqueous solution containing an inorganic acid, a cupric ion source, a halide ion source, and a polymer. The polymer has a functional group containing a nitrogen atom. It is preferable that the microetching agent contain a sulfate ion source.