To provide an external force detection device that can detect external force applied to a piezoelectric element easily with high precision and also can remove adverse influence of stress originating from the mass of an excitation electrode.

One end of a crystal piece 2 is bonded to a base 8 provided in a container 1 with a conductive adhesive 7. An excitation electrode 4 is installed on the base 8 not in contact with the conductive adhesive 7 and connected to a lead-out electrode 51 on an upper surface of the crystal piece 2 through a conductive path 14, and the lead-out electrode 51 is routed to a movable electrode 5 below the other end of the crystal piece 2. An excitation electrode 3 is provided on an upper surface in the container 1 and vertically above the excitation electrode 4, and a fixed electrode 6 is provided on a lower surface in the container 1 and right below the movable electrode 5, the excitation electrode and the fixed electrode being connected to an oscillation circuit 17 respectively. Consequently, only the movable electrode 5 and the lead-out electrode 51 are present on the crystal piece 2, and the excitation electrodes are space electrodes.