Polymer production method and radical polymerization initiating group-containing compound

Provided are: a novel production technique of allowing production of a polymer of which the molecular weight or the molecular weight distribution is controlled or allowing production of a desirably controlled polymer having a complicated structure, using commercially available materials without using any radical polymerization initiator or any special materials for use in living radical polymerization and without the need of strict polymerization conditions; and a radical polymerization initiating group-containing compound for use in the technique. The present invention pertains to: a polymer production method comprising a polymerization step for mixing and heating (1) a radical polymerizable monomer, (2) an organic compound having introduced in a single molecule thereof at least one group having a structure that is represented by general formula 1 and/or general formula 2 (in the formulae, X represents Cl or Br) and that functions as a group for initiating polymerization of the monomer, and (3) an iodine ion-containing compound, so that radical polymerization accompanied by termination starts from the group having the structure; and said organic compound (2) for use in the method.