The present invention relates to a polymerization reactor. The polymerization reactor according to one aspect of the present invention comprises: a housing including a supply part for supplying a reactant; a tube which is provided inside the housing and extends along the height direction of the housing; a first impeller including a blade which spirally surrounds the tube along the height direction of the housing; a second impeller which is provided inside the housing in order to enable the reactant to flow into the tube; and a partition wall which is provided to surround the second impeller along the circumferential direction.