A step-up ripple free converter applied to achieve a characteristic of zero-ripple voltage, which ripple voltage is near zero, includes a ripple-regulating component, a power isolating and converting unit, a power switch, first to fourth capacitors, an auxiliary inductor, a first rectifying switch, and a second rectifying switch. The power isolating and converting unit is electrically connected to the ripple-filtering inductor, and includes a plurality of windings for separating the step-up ripple free converter into an input stage and an output stage. The power switch, the first capacitor, and the second capacitor are arranged at the input stage and are electrically connected to the power isolating and converting unit. The third capacitor, the fourth capacitor, the first rectifying switch, and the second rectifying switch are arranged at the output stage and are electrically connected to the power isolating and converting unit.