A method for manufacturing a quartz crystal unit comprises disposing a metal film on a surface of a quartz crystal wafer, disposing a resist on the metal film, forming a tuning fork shape pattern on the surface, etching the quartz crystal wafer to form a quartz crystal tuning fork shape having a base and first and second tines, forming electrodes on opposite side surfaces of the first and second tines so that the electrode of the first tine has an electrical polarity opposite to an electrical polarity of the electrode of the second tine to form a quartz crystal tuning fork resonator that vibrates in a flexural mode of an inverse phase, removing the resist before forming the electrodes, mounting the tuning fork resonator on a mounting portion of the case, disposing a metal or a glass into a through-hole of the case, and adjusting an oscillation frequency of the tuning fork resonator.