The vast majority of research studies utilize the Maslach Burnout Inventory (MBI) research tool to evaluate employee burnout. The Oldenburg Burnout Inventory (OLBI) is a recent self-report research tool for measuring professional burnout. It has two dimensions, exhaustion and disengagement from work. This questionnaire has not been extensively exploited in the field of education in Greece and its factor structure, as a research tool, has not been adequately evaluated. The purpose of this study is to evaluate the factorial structure of the OLBI research tool for mapping professional burnout in the field of education in Greece. The research was quantitative using the OLBI questionnaire. Data were collected from 66 school principals in the Secondary Education out of a total of 67 school principals of all schools in the prefecture of Ilia, in the school year 2017-2018. Data analysis and the evaluation of the factorial structure of the OLBI questionnaire were done using SPSS25 and LISREL 8.8. The results of the confirmatory factor analysis showed that the OLBI questionnaire is confirmed as a research tool for evaluating professional burnout in the field of education in Greece.