Surface acoustic wave device, surface acoustic wave apparatus, and communications equipment

A surface acoustic wave apparatus, comprising:

• a surface acoustic wave device having an IDT electrode, an input electrode section, and an output electrode section that are formed in a filter region on one main surface of a first substrate composed of a piezoelectric member, a second substrate composed of a material having a lower dielectric constant than that of the first substrate joined to the other main surface of the first substrate, and a conductor layer formed throughout a surface of the second substrate opposite to the surface joined to the first substrate, wherein the second substrate is a multilayer substrate, and
• a mounting substrate,
• wherein the surface acoustic wave device is mounted on the mounting substrate with the main surface, on which the filter region is formed, of the first substrate in the surface acoustic wave device opposed thereto.