A Drill Instructor is a Staff non-Commissioned Officer or a non-commissioned officer who is a member of the police force or armed force of a country. The responsibilities of a drill instructor vary from one country to another. The drill instructors are responsible for indoctrinating the new recruits (in the military) into the practices and customs of the military force. A drill instructor approximately makes $34,653 on average per year. Marines aged between 22 and 37 are eligible to apply for this post.