A novel polyphenol compound having lipase inhibitory activity and originating in a tea; a process for producing the compound; and a food or beverage and a medicine each containing the compound. The compound is a novel dimer compound, oolongtheanin 3'-O-gallate, which is represented by the formula (1) and obtained by oxidatively polymerizing epigallocatechin 3-O-gallate, which is the main catechincomponent of oolong tea, with a tea enzyme (polyphenol oxidase). The food or beverage and the medicinal composition each contains the novel compound, inhibits meal-derived fats from being absorbed, and thereby inhibits the neutral-fat level in the blood from increasing.