According to one embodiment, a magnetic sensor includes a sensor part, a first circuit, and a second circuit. The sensor part includes a magnetic element part, first and second conductive members. The magnetic element part includes first to fourth magnetic elements. The first conductive member includes first to third conductive portions, and first and second middle portions. The second conductive member includes fourth to sixth conductive portions, and third and fourth middle portions. The first circuit is electrically connected to the third and sixth conductive portions. The first circuit is configured to supply a first current between the third and sixth conductive portions. The second circuit is electrically connected to a first connection point and a second connection point. The second circuit is electrically connected to first and second connection points. The second circuit is configured to supply a second current between the first and second connection points.