To improve positional accuracy by installing a sensor so that its center of gravity is disposed on a vertical axis passing a spherical center under a horizontal axis passing the center in a spherical capsule, and supporting a holder case so that the capsule is rotatable to the horizontal and vertical axes.

An acceleration sensor 1 of three-axis constitution is installed so that its center of gravity is disposed on a vertical axis V passing a spherical canter in a sealed spherical capsule 8 under a horizontal axis H passing the spherical center, and the capsule 8 is supported in a holder case 9 rotatable on the horizontal and vertical axes H, V. The sensor 1 is formed as a chip, carried on a base 10 used also as a weight, and filled in the capsule 8. A power source line 11, line lead parts 13, 14 of the sensor 1 are provided at both ends of the axis H of the capsule 8. A spherical chamber 11 for containing the capsule 8 is formed at the case 9. A guide 12 for filling the parts 13, 14 is formed to protrude. Viscous liquid is charged in the chamber 11.