Method for producing polymer and apparatus for producing polymer

An apparatus for producing a polymer by a polymerization reaction that occurs in a flow path through which a fluid including three types of raw materials including at least one type of monomer, a ligand, and a metal catalyst flows, the apparatus comprising:

• a flow path;
• a liquid feeder configured to separately feed one fluid including some of the three types of raw materials and another fluid including remaining one or more of the three types of raw materials, to the flow path;
• a mixer configured to be disposed on an upstream side in the flow path and form a mixed fluid including the three types of the raw materials fed from the liquid feeder;
• a slug flow former configured to be disposed downstream of the mixer in the flow path;
• an insoluble fluid introduction unit configured to introduce an insoluble fluid that is insoluble in the mixed fluid into the slug flow former;
• and
• a controller,
• wherein
• the slug flow former merges the mixed fluid and the insoluble fluid so as to form a slug flow, and
• the controller controls a flow rate of the mixed fluid to cause the mixed fluid to reach the slug flow former within a predetermined time from the mixer.