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