Disclosed herein is a pulse transformer that includes: a drum core including a winding core part and first and second flange parts provided at both ends of the winding core part in an axial direction; a plurality of wires wound around the winding core part; and a plate-like core fixed to the drum core so as to face a first surface of the first flange part that is parallel to the axial direction and a second surface of the second flange part that is parallel to the axial direction. A value of S1/S2 is 0.19 or more and 0.47 or less, where an area of the cross section of the winding core part that is perpendicular to the axial direction is S1 and a facing area between the plate-like core and the first or second surface is S2.