PROBLEM TO BE SOLVED: To provide a producing method of polyphenol compound containing plant in which plant containing increased polyphenol compound amount than normal amount may be efficiently produced, a method of increasing amount of polyphenol compound in polyphenol compound containing plant, a method of increasing amount of tricaffeoylquinic acid in tricaffeoylquinic acid containing plant and a tricaffeoylquinic acid containing plant.SOLUTION: There is provided a producing method and application thereof of polyphenol compound containing plant containing increased polyphenol compound amount than a plant subjected to root part removing step, comprising a root part removing step in which root part of grown polyphenol compound containing plant selected from a group consisting of potatoes other than sweet potato, convolvulaceae plant and asteraceae plant and a preserving step in which the plant from which root part is removed is preserved under the presence of water, at 20°C to 40°C, for 24 hours or more.SEL
