It has the function of supplying oxygen sufficiently to peripheral cells, has little damage or damage to cells under hypoxic or anaerobic stimulation, has a sufficiently high effect of protecting cells, and has a stable effect. A biologically administrable aqueous solution and a method for producing the same are provided. The biologically administrable aqueous solution of the present invention contains oxygen nanobubbles, and the average particle size and density of the oxygen nanobubbles are 30 nm or less and 1016 or more per ml, respectively, as measured with a cryo-transmission electron microscope by the ice embedding method. , Preferably 1 to 10 nm and 1017 or more per ml. The biologically administrable aqueous solution of the present invention is an aqueous solution containing dissolved oxygen injected from the outside of a cylinder having two or more through-holes in the circumferential direction through the through-holes at a pressure equal to or higher than atmospheric pressure. And oxygen nanobubbles generated by colliding so that water hammer is concentrated on the center of the cylinder on the same plane parallel to the surface.末梢細胞に酸素を十分に供給する機能を有し、低酸素性又は嫌気性の刺激下において細胞の損傷又は障害が少なく、細胞を保護する効果が十分に高く、安定的な効果が持続して得られる生体投与可能な水溶液及びその製造方法を提供する。本発明の生体投与可能な水溶液は、酸素ナノバブルを含み、氷包埋法によってクライオ透過型電子顕微鏡で測定したときの前記酸素のナノバブルの平均粒径及び密度がそれぞれ３０ｎｍ以下及び１ｍｌあたり１０１６個以上、好ましくは１～１０ｎｍ及び１ｍｌあたり１０１７個以上である。本発明の生体投与可能な水溶液は、溶存酸素を含む水溶液を、２以上の貫通小穴を周方向に有する筒の外部から該貫通小穴を通して大気圧以上の圧力で噴射させ、前記筒の径方向断面と平行な同一平面上で前記筒の中心に水撃が集中するように衝突させて発生させた酸素ナノバブルを含む。
