A plurality of IDT electrodes 2 to 7 each having a large number of
electrode fingers extending in a direction perpendicular to a propagation
direction of a surface acoustic wave propagating on a piezoelectric
substrate 1 are arranged on the piezoelectric substrate 1 along the
propagation direction, and each of the two adjacent IDT electrodes out of
the plurality of IDT electrodes 2 to 7 comprises a variable pitch section
and a fixed pitch section. The electrode finger pitch in the variable
pitch section gradually decreases toward the boundary between the two
adjacent IDT electrodes, and the minimum electrode finger pitch portion
in the two variable pitch sections is on one side spaced apart from the
boundary. There can be provided a surface acoustic wave apparatus having
a large pass bandwidth, having a low insertion loss, and having improved
flatness in a pass band.