To provide an ozonized water producing apparatus capable of efficiently and easily producing ozonized water with a high dissolution degree and a high concentration. In an ozonized water producing apparatus constituted by including a pipeline for passing water to be treated through, a gas-liquid mixing structure provided halfway in the pipeline, and an ozone supply structure for supplying ozone into the gas-liquid mixing structure, the gas-liquid mixing structure is provided with a magnet for exerting a magnetic force onto an inside. By causing the magnetic force to act on both the water to be treated and ozone, ozonized water with a high dissolution degree and a high concentration can be efficiently and easily produced.