PROBLEM TO BE SOLVED : To provide a novel simple and efficient production method for a flavonoid clathrate compound and a flavonoid glycoside composition that are excellent in solubility in water, to provide a flavonoid clathrate compound excellent in solubility in water, a flavonoid clathrate compound-containing composition, an isoquercitrin glycoside composition, a hesperetin-7-glucoside glycoside composition, and a naringenin-7-glucoside glycoside composition, to provide food and drinks, medical supplies, or cosmetics which comprise these compounds or compositions, and to provide a method for improving the solubility of poorly soluble flavonoid. SOLUTION : Provided is a method for producing a flavonoid clathrate compound comprising a desorption step of treating a poorly soluble flavonoid having a rhamnoside structure with an enzyme having rhamnosidase activity in the presence of cyclodextrin to desorb rhamnose. SELECTED DRAWING : None COPYRIGHT : (C)2019, JPO&INPIT