An IT-cut quartz crystal unit has a discoidal or a rectangular quartz crystal blank which is cut from a crystal of quartz along a plane perpendicular to the Y-axis of the crystal of the quartz which is rotated over approximately 34null about the X-axis, and further rotated from this rotated position over approximately 19null about the Z-axis. Excitation electrodes are formed on both main surface of the crystal blank, respectively. The crystal blank is held at positions in at least one set of opposing peripheral regions selected from an angular range of 18nullnull18null from the Znull-axis on the surface of the crystal blank, viewed from the center on the surface of the crystal blank; an angular range of 198nullnull18null from the Znull-axis; an angular range of 108nullnull18null from the Znull-axis; and an angular range of 288nullnull18null from the Znull-axis.