PURPOSE: To provide the titled binder enabling the enhancement of recording sensitivity, constituted of a copolymer of (meth)acrylamide and hydroxyalkyl (meth)acrylate.

CONSTITUTION: The binder for a thermal recording material consists of a copolymer of 35W65wt% of (meth)acrylamide and 65W35wt% of hydroxymethyl (meth)acrylate or hydroxypropyl (meth)acrylate. This copolymer can develop excellent effect for enhancing recording sensitivity not obtained by a conventional binder. In addition, although this binder has a high M.W., an aqueous solution thereof shows low apparent viscosity and, therefore, when said copolymer is used as a binder, excellent coating properties are obtained.