A duplexer includes two surface acoustic wave (SAW) filters having different center frequencies; a phase matching circuit that matches phases of the two SAW filters; a package in which the SAW filters and the phase matching circuit are housed, the package being composed of multiple layers; and a line pattern provided between at least one of the SAW filters and at least one of a transmit terminal and a receive terminal of the duplexer. The line pattern runs on at least two of the multiple layers within a range defined by peripheral ground patterns provided in the package.