PROBLEM TO BE SOLVED: To provide a low-cost oxygen generator capable of directly feeding oxygen to a water environment, satisfactory in oxygen dissolution controllability, excellent in controllability, also controlling a water environment comfortably and satisfactorily to useful water zone products, capable of realizing the purification of a water environment without a filter, and operable stably over a long time with almost no-noise.SOLUTION: Provided is an oxygen generator used for a water environment 2 comprising: at least two electrode means 1a, 1b installed so a to be immersed into the water of a water environment 2； a potential set means 4 for causing a potential difference between the electrode means 1a, 1b； an electrode polarity switch means 5 for switching the polarities of the electrode means 1a, 1b； an electrode current control means 6 deciding a potential difference set between the electrode means 1a, 1b by the potential set means 4 utilizing information regarding current value to the electrode means 1a, 1b； and a power feed means 8 for feeding power to the potential set means 4, in which the electrode means 1a, 1b electrically decompose a part of the water of the water environment 2, and the oxygen content included in the water of the water environment 2 is increase or maintained.SELECTED DRAWING: Figure 1【課題】水環境へ直接的に酸素を供給可能で、酸素溶解効率が良く可制御性に優れ、かつ、水環境を有用水圏生物にとって快適・良好に整え、水環境の浄化が濾過装置なしで実現できる、殆ど無騒音で長期間安定的に動作可能な低コストの酸素発生装置の提供。【解決手段】水環境２に用いる酸素発生装置において、水環境２の水に浸漬するように設置した少なくとも２つの電極手段１ａ、１ｂと、電極手段１ａ、１ｂ間に電位差を生じさせるための電位設定手段４と、電極手段１ａ、１ｂの極性を切り換えるための電極極性切り換え手段５と、電位設定手段４が電極手段１ａ、１ｂ間に設定する電位差を、電極手段１ａ、１ｂへの電流値に関する情報を利用して決定する電極電流制御手段６と、電位設定手段４に電力を供給する為の電力供給手段８を備え、電極手段１ａ，１ｂが水環境２の水の一部を電気分解し、水環境２の水に含まれる酸素量を上昇させる又は維持する酸素発生装置。【選択図】図１
