To prepare polymer beads having a uniform particle size and quality in a short period of time by suspension polymerisation with simple operations and high cost effectiveness.

The method comprises: jetting a monomer solution into an upward flow in a pulsating manner from an opening having a diameter of 50-300 micron in a reaction vessel bottom part at a flow rate of 2-4 L/hr and at a pressure of 0.2-1 kg/cm² while, in parallel therewith, jetting a monomer-immiscible liquid solution into the upward flow in a pulsating manner through holes having a diameter of 0.5-1 mm provide at the upward outer periphery of the opening at a flow rate of 4-8 L/hr and at a pressure of 2.5-3 kg/cm² where a ratio of the monomer solution to the liquid solution is 1:4-1:10, and the holes are positioned above the opening at a distance of 10-40 mm; stabilizing monomer liquid droplets in the liquid solution by partial polymerization in the reaction vessel while raising the droplets in the reaction vessel without coagulating the monomer droplets under kinetic external force caused by flow rate differences and the like of respective solution-supplying parts; and polymerizing the monomer liquid droplets in a polymerization reaction vessel disposed in a position higher than that of the reaction vessel.