A micromachine successfully reduced in parasitic capacity between input and output electrodes, and having an oscillator configured as ensuring a high S/N ratio under operation at higher frequencies is disclosed. The micromachine comprises an insulating layer formed on a substrate; a first electrode for signal input formed on the insulating layer; a second electrode for signal output formed on the insulating layer; and an oscillator electrode formed as being opposed with the first electrode and the second electrode and as being spaced therefrom by an air gap, wherein the insulating layer has a groove formed therein at least between the first electrode and the second electrode.