A method for producing elliptical, needle-shaped, or rod-shaped polymer particles satisfying (1)-(3) below includes a step in which a synthesis solution including water, a mixed solvent of a hydrophilic organic solvent and a hydrophobic organic solvent, a polymeric stabilizer, a polymerization initiator, and an unsaturated monomer is heated, and, at least after the heating has started, the pH of the synthesis solution is adjusted to 5-9 inclusive to perform solution polymerization: (1) the average (LAV) length (L) in a two-dimensional projection diagram obtained by irradiating the particles with light from a direction orthogonal to the longitudinal direction is 0.1-80 μm; (2) the average (DAV) breadth (D) in the two-dimensional projection diagram obtained by irradiating the particles with light from the direction orthogonal to the longitudinal direction is 0.05-40 μm; and (3) the average (PAV) aspect ratio (L/D) calculated from the length (L) and the breadth (D) is 1.5-30.