PROBLEM TO BE SOLVED: To provide an aqueous solution containing extremely fine air bubbles with which water containing extremely fine bubbles can be easily utilized even if a user does not hold a microbubble generator, a method for producing the aqueous solution, and the use of the aqueous solution.SOLUTION: The aqueous solution, containing extremely fine air bubbles produced by performing a step of carrying out a treatment, in which extremely fine air bubbles with a particle having a diameter of 10 to 50 μm are released into water or an aqueous solution, and a step of adding iron of ≥0.3 ppm to the water or the aqueous solution before the treatment or during the treatment, is diluted to be used for plant cultivation or the like by a user.
