Abstract: This is a minus ion generating apparatus by which cluster ions in which minus ions and plus ions are mixed can be readily and largely fabricated and only minus ions can be separated and used. The apparatus is characterized in that a spray nozzle is connected to a gas-and-liquid separator. In order to more effectively generate the minus ions, the minus ion generating apparatus comprises a mixing flow path, a supplying flow path for fluid and a discharging flow path for fluid which are in communication with the mixing flow path. The mixing flow path comprises plural circular flow paths that are arranged in parallel and that are communicated in a radial direction; plural inlets and plural outlets formed in circular flow paths, so that the location of the inlets and the location of the outlets are mutually different in a radial direction; plural communicating flow paths by which the inlets formed in one circular flow path communicates with the outlets formed in another circular flow.