An object is to provide a crystal device that uses a mesa-structure crystal piece in which frequency adjustment is possible. A configuration is such that in a crystal device having: a crystal piece having a thick portion and a thin portion, with an excitation electrode formed on both main faces of the thick portion, and a lead out electrode electrically connected to the excitation electrode, formed on an end portion; a container main body having a concavity for accommodating the crystal piece; and a cover that is connected to an open end face of the container main body and hermetically seals the crystal piece, a frequency adjustment metal film which is electrically isolated from the excitation electrode and made independent, is formed on the thin portion of the crystal piece.