A high-frequency module comprises: a diplexer connected to an antenna terminal for branching a plurality of transmission/reception systems different in pass band from one another; switch circuits for switching the transmission/reception systems to transmission systems and reception systems; power amplifiers for amplifying transmission signals in the pass bands of the transmission systems; and matching circuits for matching the impedances of the power amplifiers to one another. The power amplifiers and the switch circuits are respectively formed by high-frequency semiconductor integrated circuit elements, and these high-frequency semiconductor integrated circuit elements are mounted on the surface of the multi-layer substrate. The high-frequency module is reduced both in size and loss and increased in isolation in its entirety.