To provide a new N-vinylamide polymer in which the content of impurities is reduced, of which discoloration is reduced, which has a heightened K-value, and which is suitably usable in various kinds of fields such as a cosmetic and a medicine; and to provide a method for producing the polymer.

The N-vinylamide monomer containing an N-vinylamide monomer unit as an essential component has ≥60 K-value, ≤0.02 mass% content of a hydrolyzed product of the N-vinylamide monomer and ≤0.1 mass% content of ash, and provides a 10% aqueous solution having ≤10 hue measured based on JIS K0071.