Provided is a method for manufacturing a polymer by a flow-type reaction, including introducing a liquid A containing an anionic polymerizable monomer and a non-polar solvent, a liquid B containing an anionic polymerization initiator and a non-polar solvent, a liquid C containing a polar solvent, and a polymerization terminator into different flow paths; allowing the liquids to flow in the respective flow paths; allowing the liquid A and the liquid B to join together at a joining portion; allowing a conjoined liquid MAB of the liquid A and the liquid B to join with the liquid C at downstream of the joining portion; subjecting the anionic polymerizable monomer to anionic polymerization while a conjoined liquid MABC of the conjoined liquid MAB and the liquid C is flowing to downstream in a reaction flow path; and allowing a polymerization reaction solution flowing in the reaction flow path to join with the polymerization terminator so that the polymerization reaction is terminated and a polymer is obtained, in which a polarity of a solvent of the liquid MABC is made higher than a polarity of a solvent of the liquid MAB. Also provided is a flow-type reaction system suited for performing the manufacturing method.