By setting the CV value within the above range, the mechanical strength of the piezoelectric composition can be increased. When the CV value is excessively large, many amounts of components that do not contribute to the piezoelectric properties will be present in the piezoelectric composition, making the piezoelectric properties tend to deteriorate.

The method of calculating the CV value is not particularly limited as long as it is capable to measure the Mn concentration distribution in the piezoelectric composition. According to the embodiment, the CV value can be calculated by EPMA (Electron Probe Micro Analyzer) analysis as following. An area analysis is performed on a specific area in the cut surface of the sintered piezoelectric composition using an EPMA apparatus to obtain an information on the existence amount (concentration) of Mn present at the measurement point in the area.

From the information of the obtained Mn concentration, a standard deviation σ of the Mn concentration and the average value Av of the Mn concentration at each measurement point in the area are calculated, and the CV value is calculated from the following equation.
CV value (%)=100×(σ/Av)
According to the embodiment, a magnification for performing an area analysis is preferably 200 to 5000 times, and it is preferable to measure three or more fields.

An existence form is not particularly limited as long as Mn is present in the grain boundaries but is preferably present as a segregation phase including Mn. In the segregation phase, Mn may be present as an oxide of Mn or may be present as a compound with another element.