A process for producing an eriocitrin-containing material comprises the steps of: preparing an eriocitrin-containing citrus extract from a citrus fruit using an extractant; and separating eriocitrin from the citrus extract. The step of separating eriocitrin from the citrus extract comprises the steps of: bringing the citrus extract into contact with a porous synthetic adsorption resin such that eriocitrin in the citrus extract is adsorbed on the porous synthetic adsorption resin, the porous synthetic adsorption resin comprising a phenol-formaldehyde resin as a main framework and having amino and phenolic hydroxyl groups; and eluting the eriocitrin adsorbed on the porous synthetic adsorption resin using an elution solvent.