This research aims to (1) study the level of teacher’s competency of the secondary education service area office in lower northeast area; and (2) study the variables affecting teacher’s competency in schools of the secondary education service area office in lower northeast area. The sample group in this research is 440 secondary school teachers of the secondary education service area office in lower northeast area in the academic year of 2020. The result of the research shows that: 1) teacher’s competency in schools of the secondary education service area office in lower northeast area is at a good level. This characteristic of each teacher is slightly different; 2) teacher’s competency in schools of the secondary education service area office in lower northeast area is affected directly by teacher’s self-development, the using of technology in learning management of teacher, and the being of vocational learning community of school. These 3 variables are useable to explain 68% of variance of teacher’s competency, with statistical significance at .01, and indirectly influenced by the using of technology in learning management of teacher and the being of vocational learning community of school via teacher’s self-development.

Keywords : Competency, Self-Development, Secondary School.