Crystal resonator

A crystal resonator includes a flat plate-shaped crystal element and excitation electrodes. The crystal element has principal surfaces parallel to an X′-axis and a Z′-axis. The X′-axis is an axis of rotating an X-axis in a range of 15 to 25 degrees around a Z-axis. The Z′-axis is an axis of rotating the Z-axis in a range of 33 to 35 degrees around the X′-axis. The excitation electrodes are formed on the respective principal. The excitation electrodes include a first region with a circular outer shape and a second region. The second region is formed at a peripheral area of the first region. The second region has a thickness thinner than the first region and has an elliptical outer shape. The elliptical shape has a long axis extending in a direction in a range of −5 to +15 degrees with respect to a direction that the X′-axis extends.