Surface acoustic wave device and environmental difference detecting apparatus using the surface acoustic wave device

A surface acoustic wave device, comprising:

• a three-dimensional substrate having a surface, which includes at least a part of an annular curved surface formed with a continuous curved surface enabling to propagate a surface acoustic wave;
• and an electro-acoustic transducing element, which excites the surface acoustic wave along the surface, which propagates the surface acoustic wave along the surface, and which enables to receive the surface acoustic wave propagating along the surface, wherein the three-dimensional substrate is made of a LiNbO3 crystal, and, along the surface of the three-dimensional substrate, the electro-acoustic transducing element propagates the excited surface acoustic wave along at least one of two lines of intersections, one of which is defined between one crystal face of the LiNbO3 crystal and the surface thereof, a normal line of the one crystal face being a crystal axis specified by rotating a +Y axis that is a crystal axis of the LiNbO3 crystal by 20° in a +Z direction with an X axis being a rotational center, and the other of which is defined between the other crystal face of the LiNbO3 crystal and the surface thereof, a normal line of the other crystal face being a crystal axis specified by rotating a +Y axis that is a crystal axis of the LiNbO3 crystal by 26° in a −Z direction with an X axis being a rotational center, and the at least one of the two lines of intersections defined as an outermost circumferential line.