Disclosed are a magnetic sensing element in which side reading can be prevented, read sensitivity can be improved, and gap narrowing is enabled, and a method for fabricating the same. A magnetic sensing element includes a pair of first antiferromagnetic layers separated by a first spacer section. A first spacer layer is disposed in the first spacer section. The first spacer layer has the same composition as that of the first antiferromagnetic layers, and has a disordered crystal structure with a thickness that is smaller than that of the first antiferromagnetic layers. A first free magnetic layer is disposed on the continuous surface including the upper surfaces of the first antiferromagnetic layers and the first spacer layers. The magnetic sensing element also includes a nonmagnetic interlayer, a second free magnetic layer, and a pair of second antiferromagnetic layers separated by a second spacer section on the second free magnetic layer.