Disclosed are a toner for developing an electrostatic latent image and a method of preparing the toner. The toner may include a latex, a colorant and a releasing agent, and may further include sulfur (S), iron (Fe) and silicon (Si). The [S]/[Fe] ratio may be within the range between about 5.0.times.10.sup.-4 and about 5.0.times.10.sup.-2. The [Si]/[Fe] ratio may be within the range of between about 5.0.times.10.sup.-4 and about 5.0.times.10.sup.-2. [S], [Fe] and [Si] are the amounts of S, Fe and Si measured by X-ray fluorescence spectrometry, respectively.