According to one embodiment of the invention, a magnetic sensor includes a first sensor part. The first sensor part includes a first magnetic member, a first counter magnetic member, and a first magnetic element. A direction from the first magnetic member to the first counter magnetic member is along a first direction. The first magnetic element includes one or a plurality of first extending portions. A first portion of the first extending portion overlaps the first magnetic member in a second direction crossing the first direction. A first counter portion of the first extending portion overlaps the first counter magnetic member in the second direction. A first direction length along the first direction of the first extending portion is longer than a third direction length along a third direction of the first extending portion. The third direction crosses a plane including the first direction and the second direction.