You should study film in order to become a director. While not always a requirement, most directors obtain a bachelor's degree in film prior to working as a director.
A bachelor's degree in film can prepare aspiring directors through the study of specialized skills related to filmmaking. Students will study script writing, cinematography, and audio production. While all of these skills are executed by specialists on a film set, it is important that film directors are familiar with how these specialized areas work together to create a film.
The benefits of film school can extend beyond the coursework. Film school offers aspiring filmmakers access to expensive equipment that they may otherwise not be able to afford. Sound equipment, film editing software, and professional lighting are a few of the advantages that students have access to as film students.
A very important part of filmmaking is developing connections that you have made within the industry. Film school provides opportunities to network with other film students and professionals in order to develop these relationships. While in film school, students, through networking and coursework, often find the specific area of film directing that they are most interested in such as documentary or television.