Abstract: A handy oxygen generator containing an oxygen generating agent which reacts with water to evolve oxygen can arbitrarily supply plenty of oxygen under all circumstances at any time. The oxygen generator can be efficiently used particularly in life-threatening emergencies such as a fire and other accidents or when climbing a mountain or playing a sport. The oxygen generator may be formed of a sealed container partitioned into two chambers separately containing water and the oxygen generating agent, so that the separately contained oxygen generating agent and water can be mixed to react with each other by easily breaking the partition with an external pressure force. The oxygen generator containing beforehand the water along with the oxygen generating agent is very convenient to carry because it has no need of procuring water.