According to freud, the part of the mind that is an impulsive mechanism is the:

The impulsive mechanism described by Freud is known as the Id. According Freud, the id is the unconscious part of the human mind that wanted to be satisfaction that holds hidden instincts and desire for action.  He said that for some people this is not suppressed and are controlled by their Id. This shows their negative behavior without any sense of undertanding right decisions.