Herein are disclosed a process for producing xylitol of high purity (one-step desalting process) which comprises the steps of (1) removing the solid matter from a culture froth obtained by culturing a xylitol-producing microorganism in an aqueous culture medium, (2) desalting the resulting solid matter-removed culture broth by removing the ionic substances therefrom by means of a cation-exchange resin and an anion-exchange resin, (3) subjecting the resulting desalted solution to the chromatography using a strongly acidic cation-exchange resin to separate the xylitol from the other sugar alcohol(s) and sugar(s), and (4) obtaining the xylitol by separating it at a high purity from the resulting xylitol solution (fraction), and to a similar process (two-step desalting process) but wherein the desalting carried out twice by adding the ion-exclusion step between Steps (1) and (2) of the above-mentioned process, whereby most of the ionic substances are removed, by which processes highly pure xylitol can be obtained from a xylitol solution in a commercially effective way, in the method for producing xylitol by using a xylitol-producing microorganism.