but may be formed with two or more kinds of materials in other words two kinds of frequency adjustment films 5 that are in contact with the sio 2 film 4 on a single piezoelectric substrate wafer 2 can be formed so as to have different acoustic velocities among resonators on a wafer for example for a resonator whose resonant frequency is higher than the center frequency the frequency adjustment films 5 can be formed with a material having a higher acoustic velocity than the material of the sio 2 film 4 on the other hand for a resonator whose resonant frequency is lower than the center frequency the frequency adjustment films 5 can be formed with a material having a lower acoustic velocity than the material of the sio 2 film 4 for example in the case where resonators on a wafer before the frequency adjustment films 5 are formed have the same frequency as a center frequency it is believed that a region having a frequency higher than the center frequency and a region having a frequency lower than the center frequency coexist in terms of the in plane distribution of frequencies in the wafer in such a case the in plane distribution can be improved by providing both a frequency adjustment film made of a material having a higher acoustic velocity than sio 2 and a frequency adjustment film made of a material having a lower acoustic velocity than sio 2 on a single wafer accordingly the distribution of acoustic velocities in the frequency adjustment films 5 can be made to correspond to the frequency distribution of an acoustic wave on a single substrate wafer as a result an acoustic wave device in which the in plane.