A method for producing an oscillator includes: (a) forming a first layer on a substrate; (b) ion implanting a first impurity into a first region of the first layer; (c) forming a first electrode having a tapered plane on a side surface thereof by patterning the first layer; (d) forming a sacrificial layer on the first electrode and on the tapered plane of the first electrode; (e) forming a second electrode on the substrate and the sacrificial layer; and (f) removing the sacrificial layer. The step (b) is performed so that the concentration of the first impurity monotonically decreases from the upper surface side to the lower surface side in a region located at a depth of more than 10 nm from the upper surface of the first electrode.