To provide a manufacturing method of a polymer containing a lactone ring which can obtain a polymer containing a lactone ring in a high lactone ring formation rate and in one step using 2-(hydroxyalkyl)acrylate as a raw material.

The manufacturing method of a polymer having a lactone ring structure comprises a lactone ring formation of a structual unit originated from a 2-(hydroxyalkyl)acrylate and solution-polymerization of a monomer component at 50-150°C using a monomer having the 2-(hydroxyalkyl)acrylate as well as a monomer having an acidic group as essential monomer components.