To provide a layered balun transformer which can be made small in size and low in height and has excellent characteristics, and to provide a high frequency switch module using the layered balun transformer.

In the layered balun transformer, each of first to fourth transmission lines constituting the balun transformer is configured by electrically and spirally connecting a plurality of conductor patterns formed on surfaces of a plurality of dielectric layers, and inductors constituted of the first to fourth transmission lines are arranged so as to be overlapped when viewed in a layering direction. The layered balun transformer includes a dielectric layer forming a part of conductor patterns constituting the first transmission line and a part of the conductor patterns constituting the third transmission line, and another dielectric layer forming a part of the conductor patterns constituting the second transmission line and a part of conductor patterns constituting the fourth transmission line.