Provided are an administrable aqueous solution to a living body and a method for manufacturing the same, the administrable aqueous solution having a function of supplying sufficient oxygen to peripheral cells, causing less damage and injury of cells under a hypoxic or anaerobic stimulation, and continuously exhibiting a sufficiently high and stable effect to protect cells. The administrable aqueous solution to a living body according to the present invention contains oxygen nanobubbles having a mean particle size of 30 nm or less and a density of 10 16 bubbles per ml, preferably a mean particle size of 1 to 10 nm and a density 10 17 bubbles or more per ml, respectively, as determined by a measurement with a cryo-transmission electron microscope by an ice-embedding method. The administrable aqueous solution to a living body according to the present invention contains oxygen nanobubbles which are generated by jetting an aqueous solution containing dissolved oxygen from the outside of a cylinder, the cylinder being provided with 2 or more small through holes formed in the circumferential direction, via the small through-holes under atmospheric pressure or higher and thus bringing the jetted solution into collision in such a manner that water hammer is concentrated at the center of the cylinder on the same plane parallel to a cross-section in a radial direction of the cylinder.
