For example, as shown in FIG. 3, the electrodes 4, 5, and 6 are preferably disposed in a region having 80% by area including the vicinity of the central portion of the surface on which the first and second piezoelectric/electrostrictive bodies 12 and 13 are formed.Moreover, when the common substrate 20 is shared by a plurality of piezoelectric/electrostrictive device units 10a to 10c as shown in F