The author has developed the concept of a novel ozone generator that adopts the O/O₃ different-space-generation system. The novel ozone generator consists of a dissociation chamber, an ejector, and an ozone formation chamber. Oxygen atoms generated from pure oxygen as the first material gas in the dissociation chamber are mixed with air as the second material gas in the ejector, and react with oxygen molecules to form ozone molecules in the ozone formation chamber. It has a high O₃ formation efficiency only in the low O₃ concentration range. For the improvement of the novel ozone generator, the author has newly proposed the concept of a O/O₃ different-space-generation system with a multi-stage reaction process. It consists of a dissociation chamber, multiple ejectors, and multiple ozone formation chambers. The oxygen atoms from the dissociation chamber are divided into parts for every stage and added to the air or the air containing O₃ at every stage. The ozone concentration is accumulated in every stage, and reaches the expected value in the last stage. According to the simulation results, the newly proposed ozone generator can generate O₃ of 3.1mol% with an efficiency of 172g/kwh. The novel ozone generator with the O/O₃ different-space-generation system has been improved to have a high O₃ formation efficiency even in the high O₃ concentration range.