Crystal resonator

A crystal resonator for inhibiting a coupling of an unnecessary vibration and a main vibration is provided, thereby ensuring reducing a CI value low. The crystal resonator (100) includes a flat plate-shaped crystal element (110) and excitation electrodes (129). 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 (120a) with a circular outer shape and a second region (120b). 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 exten