To provide a highly practical method for metallizing a plastic surface where, in a metallizing process for a chromium-free plastic surface, plating can be applied so as to sufficiently adhered to the plastic surface, and furthermore, plating is not deposited on a fixture.

In the method for metallizing a plastic surface, plastic is treated with an etching treatment liquid containing permanganate and inorganic acid, and then the treated plastic is treated with a catalyst addition increasing liquid containing a compound having selective adsorptivity to a functional group exposed to the surface, and further, with a catalyst addition treatment liquid, a catalyst is added to the plastic treated with the catalyst addition increasing liquid, and thereafter, the plastic added with the catalyst is subjected to metal plating.