From the viewpoint of a decrease in environmental impact in recent years, an object of the present invention is to effectively utilize lignin as a circulative biomass resource having high effect of reducing environmental impact. Specifically, the object is to provide a lignin derivative that can improve the dispersibility of various substances to be dispersed regardless of uses of cements, dyes, oil field drilling mud, and the like. The present invention provides a lignin derivative compound that is a reaction product of a lignin sulfonic acid-based compound with an aromatic water-soluble compound, and a dispersant containing the same. The lignin derivative compound preferably has an anionic functional group and/or a polyalkylene oxide chain.