A transformer unit 1 comprising a transformer composed of a bobbin 2 having wound therearound primary and secondary windings and a core inserted into the center of the bobbin and an electric component3 held in the outer peripheral region of the bobbin 2 and/or transformer is placed on a printed circuit board 4, lead terminals 3a of the electric component 3 are soldered to the printed circuit board4 with a solder 5, and the lead terminals 3a are sandwiched in a slit 2b formed in the bobbin 2 and are fixedly attached thereto. In this structure, a bent portion 3b for preventing the bobbin 2 from sliding, while sandwiching the lead terminal 3a, in the longitudinal direction of the lead terminal 3a is formed in the lead terminal 3a.