Provided are: an oxygen-generating composition which enables the distribution of oxygen in water in a well-balanced manner to thereby provide a stable water environment that does not become cloudy even when the oxygen-generating composition contains calcium peroxide at a small content and a method for producing the oxygen-generating composition. An oxygen-generating composition which comprises a molded article comprising 2 to 20 wt% of calcium peroxide, 2 to 30 wt% of calcium carbonate, 2 to 30 wt% of calcium hydroxide and 30 to 80 wt% of calcium dihydrogen phosphate, wherein the outer shape of the molded article has a surface area of 500 × 10-6 to 3000 × 10-6 m2 and an aspect ratio of 1.0 to 4.5 and a method for producing the oxygen-generating composition.
