A method for producing polymer particles which includes: forming polymer particles by heterogeneous polymerization of a monomer in a supercritical fluid and/or subcritical fluid, wherein a radical polymerization initiator (I) having in a molecular at least a group having radical-generation capability and a group having affinity for the supercritical fluid and/or subcritical fluid, and a radical polymerization initiator (II) are used in combination.