PURPOSE: To obtain a detector which enables accurate detection of a moving value not only in a two-dimensional direction such as that on a plane but also in a three-dimensional direction immediately.

CONSTITUTION: Planar laminated piezo-electric elements 1a-1f are built subically surrounding a mobile element 6 comprising metal, resin or the like and an electrode 2 is mounted on both side end faces of respective detection surfaces of the laminated piezo-electric elements 1a-1f. The electrode 2 is connected to a detection circuit 4 to detect a moving value. This enables accurate detection of not only a two-dimensional moving value but also a slant moving value, namely, a three-dimensional moving value immediately. In addition, a simple structure of a detector 12 allows the selection of the shape and size of the detector 12 according to the use thereof.