A method of forming a quartz crystal resonator is provided with the resonator including a body portion with first and second main surfaces facing each other and, in plan view having a pair of long sides extending in a first direction and a pair of short sides extending in a second intersecting direction. Moreover, first and second excitation electrodes are formed on the respective main surfaces; a frame surrounds the body portion at both ends and is separated from the both ends; and first and second coupling portions extend from the short sides and with widths of the short sides. At least one of the first and second coupling portions is formed with a thickness in a third direction is smaller than a thickness in the third direction of a region of the body portion where the first excitation electrode and the second excitation electrode face each other.