To obtain the subject new polymer having a structural unit represented by a specific formula, capable of further imparting heat resistance and improving strength after molding and processing and useful as a new high performance raw material.

This acrylic acid ester-based polymer has one or more structural units represented by formula I [R1 is H, a halogen, methyl, ethyl or cyano; (z) is a group of formula H (R2 to R4 are each H, a halogen, a 1-4C alkyl, a 2-5C substitutable vinyl, etc.; A, B, D to G are each a single bond, a halogen, OH or a substitutable methylene)] and preferably further has (B) a structural unit derived from a copolymerizable monomer. Furthermore, a monomer in the component B is preferably styrenes or hydroxystyrenes and e. g. 1,1- dimethyl-2-propenyl(meth)acrylate, etc., is preferably used as a monomer capable of providing the component A.