A high frequency MEMS 1 as a high frequency electrical element has a silicon substrate 2 wholly formed with an insulation film, a first signal line 4 provided on the silicon substrate 2, a second signal line 5 provided on the silicon substrate 2, the second signal line 5 crossing the first signal line 4 within a first region above the silicon substrate 2, and a dielectric film 9 interposed between the first signal line 4 and the second signal line 5, and provided on one of the first signal line 4 and the second signal line 5, within the first region, the first signal line 4 and the second signal line 5 being relatively movable in directions for a contacting approach and a mutual spacing in between.