A surface acoustic wave device comprising: a piezoelectric substrate; a cover joined to the piezoelectric substrate with a support layer therebetween and with a spacing kept therebetween; a transmission surface acoustic wave filter and a reception surface acoustic wave filter formed on a major surface of the piezoelectric substrate adjacent to the cover and surrounded by the support layer; and external electrodes provided on the side of the cover opposite that facing the piezoelectric substrate, the external electrodes including an antenna terminal electrically connected to the transmission surface acoustic wave filter and the reception surface acoustic wave filter, a transmission input terminal electrically connected to the transmission surface acoustic wave filter, and a reception output terminal (28g,h) electrically connected to the reception surface acoustic wave filter; wherein the transmission surface acoustic wave filter includes a plurality of series-connected surface acoustic wave resonators and a plurality of interconnection lines, each interconnection line electrically connecting a respective neighboring pair of said series-connected surface acoustic wave resonators, wherein the one of said interconnection lines closest to the transmission input terminal, that electrically connects one pair (210,220) of the neighboring series-connected surface acoustic wave resonators includes at least one cover line disposed on one of an upper surface and a lower surface of the cover and at least one pair of via lines that passes through at least the support layer so as to connect the at least one cover line to one (210/220) of said one pair of neighboring series-connected surface acoustic wave resonators and the other surface acoustic wave resonator (220/210). a piezoelectric substrate; a cover joined to the piezoelectric substrate with a support layer therebetween and with a spacing kept therebetween; a transmission surface acoustic wave filter and a reception surface acoustic wave filter formed on a major surface of the piezoelectric substrate adjacent to the cover and surrounded by the support layer; and external electrodes provided on the side of the cover opposite that facing the piezoelectric substrate, the external electrodes including an antenna terminal electrically connected to the transmission surface acoustic wave filter and the reception surface acoustic wave filter, a transmission input terminal electrically connected to the transmission surface acoustic wave filter, and a reception output terminal (28g,h) electrically connected to the reception surface acoustic wave filter; wherein the transmission surface acoustic wave filter includes a plurality of series-connected surface acoustic wave resonators and a plurality of interconnection lines, each interconnection line electrically connecting a respective neighboring pair of said series-connected surface acoustic wave resonators, wherein the one of said interconnection lines closest to the transmission input terminal, that electrically connects one pair (210,220) of the neighboring series-connected surface acoustic wave resonators includes at least one cover line disposed on one of an upper surface and a lower surface of the cover and at least one pair of via lines that passes through at least the support layer so as to connect the at least one cover line to one (210/220) of said one pair of neighboring series-connected surface acoustic wave resonators and the other surface acoustic wave resonator (220/210).