Abstract: A process for preparing hollow polymer particles which comprises a seed-forming step for polymerizing a monomer mixture of an acid monomer having a carboxylic acid group and a non-ionic hydrophilic monomer in the presence of a polymerization initiator; a core-forming step for preparing a core, which can be swollen with an alkali, by polymerizing the monomer mixture of an acid monomer having a carboxylic acid group, a non-ionic hydrophilic monomer and a cross-linking agent to the seed latex; a shell-forming step in which a hydrophobic shell is formed on the hydrophilic core; and an alkali-swelling step.