A gallium nitride high electron mobility transistor, in which an inner field-plate is disposed between the gate and drain of the high electron mobility transistor, so that an electric field is distributed between gate and drain regions to reduce a peak value and to reduce gate leakage current while maintaining high frequency performance, thus obtaining a high breakdown voltage, reducing the capacitance between the gate and the drain attributable to a shielding effect, and improving linearity and high power and high frequency characteristics through variation in the input voltage of the inner field-plate.