To provide a langasite single crystal wafer which has triple rotation Euler's angles, and which has both excellent surface-acoustic-wave characteristics and extremely excellent and stable accuracy of orientation working, and to provide a method for manufacturing the same.

The langasite single crystal wafer has triple rotation Euler's angles (30°, 20°≤θ≤30°, ψ). The method for manufacturing the wafer is carried out as follows: a langasite single crystal is grown; the plane index [113] or [225] of the langasite single crystal is specified by means of X-ray diffraction measurement; and the langasite single crystal is worked into the langasite single crystal wafer, making the plane index [113] or [225] an orientation reference for a wafer plane.