A magnetic substance detection sensor includes a first support substrate, a magnet disposed on the upper main surface of the first support substrate so that a magnetization direction becomes parallel to the upper main surface of the first support substrate, a semiconductor chip disposed on the upper main surface of the first support substrate and having a magnetic field detection element configured to detect a magnetic field component in a specific direction, and a soft magnetic substance film disposed on the lower main surface of the first support substrate and extending in a direction parallel to the magnetization direction of the magnet.