The human factor within the school unit is a lucrative investment, which it yields for a long time to the school unit or to the totality of the education system. Of course, in our country, the educational unit is the ultimate recipient of educational policy decisions, as our education system is centralized. Executives and teachers are the implementers of the decisions of the Ministry of the Interior. A fact that often leads educators to feel work stress in international and Greek surveys. The present study aims to explore the behavior of students as a stress factor. For this reason, a quantitative survey (with a questionnaire of 1.988 primary school teachers) was carried out between November 2015 and January 2016. The findings reveal a great deal of stress about student behavior as a stress factor. This article will present the stress factor, student behavior as a source of teacher stress.