There is provided a transformer in which lead wires of a coil are disposed to be separated from each other so as to prevent a short-circuit between the lead wires. The transformer includes a winding unit having a plurality of partitions formed on an outer circumferential surface of a tubular body part; a base provided at one end of the winding unit and including at least one external connection terminal protruding outwardly; a coil wound on a bobbin and having a lead wire connected to the external connection terminal; and a core electromagnetically coupled with the coil to thereby form a magnetic path, wherein the bobbin includes at least one lead wire supporting portion protruding outwardly from the partitions, supporting the lead wire and guiding the lead wire to the external connection terminal.