A branching filter comprising: a receiving filter chip (12; 32); and a transmitting filter chip (11; 41), the transmitting filter chip being an acoustic wave filter chip, the receiving filter chip being an acoustic wave filter chip, wherein the transmitting filter chip includes a first piezoelectric substrate, at least one IDT disposed on the upper surface of the first piezoelectric substrate, and a first insulating layer which extends over the IDT or which is disposed above the IDT; the receiving filter chip includes a second piezoelectric substrate, at least one IDT disposed on the upper surface of the second piezoelectric substrate, and a first insulating layer which extends over the IDT or which is disposed above the IDT; the transmitting and receiving filter chips are arranged such that the upper surfaces of the first and second piezoelectric substrates are located upward; the transmitting and receiving filter chips each include a second insulating layer disposed on a corresponding one of the first insulating layers, at least one third insulating layer disposed on the upper surface of the second insulating layer, an external terminal which is disposed on the upper surface of the third insulating layer and which is to be externally electrically connected, and a conductor (15, 16) which has one end connected to the external terminal and another end electrically connected to the IDT and which extends in the first and second insulating layers; and the conductor has a portion which extends in the first and second insulating layers, which is made of metal primarily comprising a plating film; wherein the second insulating layer of the transmitting filter chip and the second insulating layer of the receiving filter chip are connected to each other, whereby the transmitting and receiving filter chips are unified. a receiving filter chip (12; 32); and a transmitting filter chip (11; 41), the transmitting filter chip being an acoustic wave filter chip, the receiving filter chip being an acoustic wave filter chip, wherein the transmitting filter chip includes a first piezoelectric substrate, at least one IDT disposed on the upper surface of the first piezoelectric substrate, and a first insulating layer which extends over the IDT or which is disposed above the IDT; the receiving filter chip includes a second piezoelectric substrate, at least one IDT disposed on the upper surface of the second piezoelectric substrate, and a first insulating layer which extends over the IDT or which is disposed above the IDT; the transmitting and receiving filter chips are arranged such that the upper surfaces of the first and second piezoelectric substrates are located upward; the transmitting and receiving filter chips each include a second insulating layer disposed on a corresponding one of the first insulating layers, at least one third insulating layer disposed on the upper surface of the second insulating layer, an external terminal which is disposed on the upper surface of the third insulating layer and which is to be externally electrically connected, and a conductor (15, 16) which has one end connected to the external terminal and another end electrically connected to the IDT and which extends in the first and second insulating layers; and the conductor has a portion which extends in the first and second insulating layers, which is made of metal primarily comprising a plating film; wherein the second insulating layer of the transmitting filter chip and the second insulating layer of the receiving filter chip are connected to each other, whereby the transmitting and receiving filter chips are unified.