The present invention provides a process for purifying methionine. A methionine product having a purity of up to 99% or higher is obtained by separating methionine from a salt by-product through a process comprising adsorption and desorption using a macroporous adsorption resin, where the methionine content in the salt by-product is ≤0.03%. The yield of methionine extracted with the resin is up to 98% or higher. By using the process of the present invention, the existing production process is simplified, the quality of the methionine product is improved, and the production costs for methionine are reduced.