The contents by weight ratio of lanthanum oxide, gallium oxide, and silicon oxide, which are components, in the longitudinal cross-section and transverse cross-section of the straight part, excluding the shoulder part, of a Langasite single crystal ingot grown by pulling-up Langasite is within a range of .+-.0.05% with respect to the target amounts at all measured locations, and because of having a superior homogeneity in the content of components over the entire ingot, when used, for example, in a piezoelectric device such as an surface acoustic wave filter, has properties for industrial application that contribute to the stabilization of characteristics as well as reducing the costs.