A method of manufacturing a piezoelectric element including a step of preparing a green sheet A including a portion which becomes a fired piezoelectric body later, by use of a piezoelectric material; a step of joining, to at least one surface of the green sheet A, a green sheet B having an opening in a portion facing the portion which becomes the fired piezoelectric body later, followed by firing to obtain the fired piezoelectric body provided with a reinforcing plate to which the reinforcing plate formed owing to the firing of the green sheet B is attached; and a step of forming a film-like electrode in a portion obtained by the firing of the green sheet A in the fired piezoelectric body provided with the reinforcing plate.