Abstract: The present invention relates to an ozone generating apparatus most suitable for use for a water quality improving apparatus by which the amount of oxygen dissolved in water is increased, and chlorine or carcinogenic noxious substances such as trihalomethanes contained in city water are decomposed.In the present invention, a ultraviolet generating means is formed in a container body, a pipe member is arranged to extend through said container body, and a part of the pipe member that is located in said container body is formed with a plurality of hole members thereby allowing the ozone generated by the ultraviolet generating means to be sucked through the hole members and to be transported.Projections for reducing the pipe cross sectional area are formed on the inner wall of the pipe member adjacent to the holes to extend in the direction from the connection of the pipe member with a gas supplying means toward the hole members, so that the sucking force of ozone can be improved.