Core-shell latex polymer is produced that includes a crystalline polymer. The core-shell latex polymer includes the crystalline polymer, a base monomer, a dispersing agent, an initiator and distilled water. The crystalline polymer serves as the core of the resulting polymer particle. The core-shell latex polymer including the crystalline polymer having a low melting point is used in a toner. A latex polymer including a releasing agent is easily prepared without using high temperatures or a high speed dispersing device. The crystalline polymer efficiently coagulates with other particles in the toner. In addition, the fixing temperature may be reduced when the toner is used in an image forming device.