The present invention relates to an apparatus for generating high frequency electromagnetic field with adjustable magnetic field intensity and waveform and water purification system comprising the same. The apparatus for generating high frequency electromagnetic field is comprising of a user input unit into where the user can input; a quantum field generator for generating a quantum field of high voltage which is capable of adjusting output voltage; a wave generator for generating high-frequency signals of variable waveforms and matching with the quantum field; a high-frequency output unit for scanning the matched quantum field of high frequency; and a controller that controls magnitude of output voltage from the quantum field generator and output frequency from the wave generator. Therefore, the present invention provides the apparatus for generating high frequency electromagnetic field with extra high voltage at low cost which can treat waste water effectively according to characteristics of a contaminant and has no fear of secondary contamination.