An electric current sensor includes a substrate, a first sloped surface, a second sloped surface, at least one conductive wire, a first anisotropic magnetoresistor (AMR) unit, a second AMR unit, a first magnetization direction setting device, and a second magnetization direction setting device. The first sloped surface and the second sloped surface are disposed on the substrate and arranged in a first direction. The at least one conductive wire extends along a second direction and is disposed beside the substrate. The first AMR unit is disposed on the first sloped surface. The second AMR unit is disposed on the second sloped surface. The first magnetization direction setting device and the second magnetization direction setting device are configured to set magnetization directions of the AMR units.