To obtain highly efficiently a polymer mixture having a narrow mol.wt. distribution through two- or higher-stage solution polymerization.

The process for producing an acrylic resin mainly from (meth) acrylic esters having a 2-14C alkyl as a side chain comprises feeding a monomer mixture in two or more portions into a batch reactor to polymerize the monomer mixture in two or more stages. At least the second and each subsequent stage are conducted using a thermally decomposable radical polymerization initiator having a 10-hr half-life temp. of 85-110°C in an amount of 0.01-0.1 pt.wt. per 100 pts.wt. the monomers. After the monomer mixture (solution) for the second or any subsequent stage has been fed into the reactor, the reaction mixture is boiled to remove substantially all the dissolved oxygen.