A magnetic film sensor comprises a magnetic film for generating a magnetostriction, and a magnetostrictive structure for generating a magnetostriction in the magnetic film. The magnetostrictive structure is constructed so as to generate a magnetostriction by curving the magnetic film, for example. The magnetostrictive structure is obtained, for example, by providing a depressed insulating layer having a surface formed with a depression and forming the magnetic film across the depression. A deformable part that is formed using a softer material than the magnetic film may also be formed at least partly on a surface of the magnetostrictive structure, within the depression.