To manufacture a polyarylenesulfonic acid, which is excellent as a production intermediate of a polyarylene having a sulfonic acid group, as a higher molecular-weight product.

The manufacturing method of the polyarylene comprises bringing a polyarylene, which is obtained by polymerizing a monomer comprising a dihalobenzene compound represented by formula (1) in the presence of a nickel compound, into contact with an oxo acid of nitrogen. In the formula, A is an amino group substituted with one or two hydrocarbons, the total of the number of carbons in the hydrocarbons being 3-20, or a 1-20C alkoxy group; R1's are the same or different and are each a hydrogen atom, fluorine atom, 1-20C alkyl group, 1-20C alkoxy group, 6-20C aryl group or the like, and two neighboring R1's may be linked together to form a ring; X1 is a chlorine, bromine or iodine atom; m is 1 or 2; and k is 4-m.