A demultiplexing circuit (10) includes a band switch (20) and a first communication band phase adjustment circuit (30). The band switch (20) includes a shared terminal (P20) connected to a shared connection end (110), a first selection target terminal (P21) connected to a second signal end (122), and a second selection target terminal (P22) connected to a third signal end (123). In the band switch (20), the first selection target terminal (P21) and the second selection target terminal (P22) are selectively connected to the shared terminal (P20) in response to the communication band to be transmitted. The first communication band phase adjustment circuit (30) is connected between a first signal end (121) and a predetermined position in a transmission path where the shared connection end (110) and the shared terminal (P20) are connected.