Abstract: The present invention provides a process and equipment for efficiently and economically recovering organic sulfur compounds in a fuel oil while maintaining the original chemical structures thereof. The fuel oil is admixed with a solvent low in solubility therein of hydrocarbons and high in solubility therein of organic sulfur compounds to effect migration of the organic sulfur compounds in the fuel oil into the solvent by making much of the nucleophilic properties of a lone pair of electrons on a bivalent sulfur atom of a sulfur-containing functional group, followed by fuel oil-solvent separation by settling out or with a centrifugal force.