Teacher turnover has been recognized as a significant problem in the education worldwide. This study focuses on exploring reasons behind the turnover intentions, and persistence of such intentions in 5-year follow-up among Finnish teachers. Longitudinal survey data were collected from Finnish comprehensive school teachers in 2010 (T1 n = 2310) and 2016 (T2 n = 1450). The results showed that 50% of the teachers had turnover intentions. Turnover intentions were remarkably persistent, but the reasons for them varied significantly. Lack of professional commitment and factors related to the school system and workload were the main reasons for teacher turnover intention. The results suggest several factors that should be improved simultaneously in the teaching profession to increase teacher job satisfaction and retention.