Patent ID: 7222535

Claim:
An acceleration sensor comprising: a housing member; a spring member attached to said housing member, said spring member having freedom in at least one direction of acceleration to be detected; a weight and magnetic field generation member fixed to said spring member; and a sole magnetic field detection sensor for each direction of acceleration to be detected, said sole magnetic field detection sensor attached to said housing member to face said weight and magnetic field generation member, said sole magnetic field detection sensor for each direction of acceleration to be detected provided with at least one multi-layered magnetoresistive effect element including a magnetization fixed layer and a magnetization free layer, wherein a direction of magnetic field applied to said at least one multi-layered magnetoresistive effect element from said weight and magnetic field generation member being perpendicular to a lamination plane of said at least one multi-layered magnetoresistive effect element when no acceleration is applied, and the sole magnetic field detection sensor for each direction of acceleration to be detected includes a plurality of multi-layered magnetoresistive effect elements connected with each other in series.