Disclosed herein is a transformer integrated with an inductor. The transformer includes a transformer unit configured to perform voltage transformation by mutual induction between first and second cores connected opposite to each other and primary and secondary coils included in a space between the first core and the second core; and an inductor unit having a third core connected to the second core and an inductor included in a space between the second core and the third core. The transformer is fabricated by physically integrating two elements having different functions into one element, thereby simplifying the configuration of a system.