<;P>;PROBLEM TO BE SOLVED: To provide a method and apparatus for producing high-concentration oxygen-dissolved water with a simple process and at a low cost, while there are a variety of conventional methods for producing high-concentration oxygen-dissolved water which cannot produce water containing sufficient oxygen or are hardly able to effect low-cost water production. <;P>;SOLUTION: Two or more swirling streams 34 having air bubbles containing oxygen are made to collide with each other so as to promote micronization of the air bubbles and dissolve a volume of oxygen in the air bubbles into the swirling streams. While both streams collide at a speed equal to the sum of the speeds of both streams, the impact becomes several times to ten-odd times the case where a single stream collides with a stationary surface. The maximum impact is imparted to each stream so that the bubbles in the stream are destructured and micronized thereby promoting the dissolution of oxygen in the bubbles into the streams. <;P>;COPYRIGHT: (C)2011,JPO&INPIT