To provide a simple and inexpensive means capable of suppressing the mixing of a gelled substance in powder-like PVP obtained by heating and drying an aqueous solution of PVP obtained by polymerizing a monomer such as N-vinylpyrrolidone or the like in an aqueous medium.

The method for manufacturing the aqueous solution of the vinylpyrrolidone-based polymer includes a step of polymerizing the monomer containing at least N-vinylpyrrolidone in the aqueous medium in the presence of hydrogen peroxide, a metal catalyst and ammonia, a step of adding a nonvolatile organic base in the aqueous solution containing the vinylpyrrolidone-based polymer obtained by the polymerization, and a step of removing the ammonia in the aqueous solution by distilling the nonvolatile organic base-added aqueous solution. The problem to be solved is achieved by the method.