PROBLEM TO BE SOLVED: To provide means for improving the concentration of a medicinal component in culturing a Glycyrrhiza plant.SOLUTION: A hydroponics method of a Glycyrrhiza plant for increasing the content of a specific medicinal component in the root comprises the steps of: (1) raising the Glycyrrhiza plant in a closed system facility under a long day condition in which a temperature of a culture medium is adjusted to 20 to 35°C (2) performing low-temperature culture in which the culture medium is controlled to 19°C or less before harvest (3) storing the root under the condition of 1 to 30°C after harvest (4) and drying the root under the condition of 20 to 50°C.