A leakage transformer is provided. The leakage transformer includes a first plate, a second plate, a plurality of winding pillars, a primary winding, a secondary winding and a plurality of magnetic shunt elements. Each magnetic shunt element is disposed between the two corresponding winding pillars, and there is a gap between every two neighboring magnetic shunt elements. Alternatively, the magnetic shunt element is disposed on the first plate and aligned with the corresponding winding pillar, and there is a gap between the magnetic shunt element and the second plate. A leakage inductance of the leakage transformer is determined by the gap.