The present invention is directed to a thin-film magnetic head having no ATE (adjacent track erase) problem, a very narrow track width, an excellent O/W (overwrite) characteristic and a high switching speed. A lower pole film of a write element is provided on one face of a lower yoke film inside a trench portion provided in an inorganic insulating film. A gap film and an upper pole film are provided inside the trench portion on the lower pole portion. The trench portion has preferably an attached film made of an inorganic material on the inner wall faces facing the side faces of said lower pole film, said gap film and said upper pole film.