A magnetic sensor includes an MR element and two stacks. The two stacks are spaced apart from each other along a first direction. Each stack includes a ferromagnetic layer and an antiferromagnetic layer stacked along a second direction orthogonal to the first direction. An element placement region is formed between the two stacks when viewed in the second direction. The element placement region includes a middle region and two end regions. The MR element is placed to lie within the middle region.