A high-frequency front-end circuit includes first and second switching circuits, first, second, and third splitters, and first and second lines. The first line is connected to the second splitter. The second line is connected to the third splitter. An adjustment circuit is connected between the first and second lines. The frequency of a harmonic signal of a transmission signal transmitted through the first line has a frequency band that is close to or overlaps the frequency of a reception signal transmitted through the second line. The impedance of the adjustment circuit is set such that a harmonic signal transmitted from the adjustment circuit to the second line and a harmonic signal transmitted from the third splitter to the second line are not in same phase with each other at the connection point between the adjustment circuit and the second line.