To detect behavior of a carrier at any inclination, especially for improved sensitivity.

Two discs 1 each of which, being a substrate with a through hole, comprises a brass cylinder 3, a conductive pattern 6 which is, stopping both opening end parts of the cylinder 3, radial in inward direction, and a cylinder seat 5 at its center, in addition, a ball 4 which acts as a moving electrode while housed in the cylinder 3 and rolled to conduct between the inside wall of the cylinder 3 and the pattern 6, an electrode 101 connected to the cylinder 3, and an electrode 102 connected to a pin 2 inserted into the through hole of the disc 1, are provided. The ball 4 does not remain at the cylinder seat 5 at the center of the disc 1 but rolls on the inside wall of the cylinder 3, so even a slow behavior is detected.