The aim of the study is to determine pre-service and high school physics teachers' ideas about simple electric circuits. In this study, a test containing eight questions related to simple electric circuits was given to the pre-service physics teachers (32 subjects) that had graduated from Balikesir University, Necatibey Faculty of Education, the department of physics education and working as physics teachers (25 subjects) in various High Schools in Turkey to determine their ideas about the same subjects. As a result, it is found that, in partial, while the physics teachers have alternate conceptions about "sequential reasoning", "source of stationary current", and "current usage", the pre-service physics teachers have unscientific ideas about "source of stationary current", "The concept of current, energy and potential differences are used one another by mistaken", "current usage" and "sequential reasoning". (Contains 6 tables.)