Abstract: Disclosed is a novel means by which cyanoacrylate polymer particles still more useful as an antibacterial agent, an anticancer agent, etc., than conventional particles. The method for production of cyanoacrylate polymer particles according to the present invention comprises anionically polymerizing a cyanoacrylate monomer(s) in the presence of at least one selected from the group consisting of amino acids, amino acid derivatives, and oligomers and polymers thereof, and substantially in the absence of a saccharide and substantially in the absence of a polysorbate. Cyanoacrylate nanoparticles containing an amino-based molecule(s) exhibit their cell-damaging activity via specific adhesion to cells, and effectively inhibit the growth of cancer cells and bacteria. Their cell-damaging activity can be further increased by producing the nanoparticles by the above-mentioned novel production method.