Disclosed are: a composition which enables the more effective development of the efficacy of a water-soluble drug in a solution containing the drug; and a dispersion in which a hydrophobic drug can be dispersed stably without requiring the use of any surfactant. Specifically disclosed are: a composition comprising ultra-fine bubbles having a mode particle size of 500 nm or less, a drug and water; and a process for producing a composition comprising ultra-fine bubbles having a mode particle size of 500 nm or less, a drug and water, which utilizes an ultra-fine bubble generation apparatus.
