PROBLEM TO BE SOLVED: To provide a method for raising rush seedlings eliminating such inconvenience in raising rush seedlings that the growth of the rush seedlings is inhibited or the rush seedlings run dry because the temperature of water in a raising seedling pool is raised in a high-temperature season in summer, so as to favorably raise the rush seedlings while preventing the water temperature from rising even in the high-temperature season in summer. SOLUTION: The method for raising rush seedlings includes: charging culture soil 13 into an upper-open raising seedling box 11 on its bottom surface having innumerable water-flow ports 11a to insert rush seedlings 1; placing the raising seedling box 11 on the bottom surface of a raising seedling pool; and setting the height of the surface of the flowing water to the intermediate part of the rush seedlings 1 to be inserted higher than the upper end surface of the raising seedling box 11 to raise the rush seedlings while propagating algae or floating grasses 14. COPYRIGHT: (C)2009,JPO&INPIT