A method for fabricating a bulk wave acoustic resonator (FBAR) which includes at least locally a partially suspended thin layer of piezoelectric material, and includes the following steps: the formation of at least one first so-called lower electrode on the surface of a thin layer of piezoelectric material; the deposition of a so-called sacrificial layer on the surface of the said thin layer of piezoelectric material and of the said first electrode defining a first set; the assembling of the said first set with a second substrate; the formation of at least one second electrode termed the upper electrode on the opposite face of the said thin layer of piezoelectric material from the face comprising the said first electrode; and the elimination of the sacrificial layer so as to unveil the said thin layer of piezoelectric material and the said first electrode and define the bulk wave resonator.