To provide a method for initiating an easy and safe atom transfer radical polymerization, capable of leaving terminal halogen groups in a high rate, and capable of solving, for example, a problem wherein the control of a polymerization rate is difficult due to the precipitation of a catalyst and the change in the amount of the catalyst, to provide a method for controlling the polymerization rate, and to show a method for improving a polymerization method.

This method for the atom transfer radical polymerization of a vinylic monomer is carried out under at least one condition selected from the group consisting of the following conditions: (1), (2), (3) and (4). (1) Under a substantially dehydrated condition. (2) Under the presence of a nitrile compound. (3) The ligand of the polymerization catalyst is added to the polymerization system to initiate the polymerization reaction. (4) The activity of a polymerization catalyst is changed during the polymerization reaction to control the polymerization rate.