The purposes of the study entitled “Competency of Public Relation Officers, Chiang Mai University”, were 1) to investigate the competency level of Public Relation Officers, Chiang Mai University 2) to study the essential competency framework of Public Relation Officers, Chiang Mai University and 3) to examine the guidelines of applying the competency concept for Public Relation Officers, Chiang Mai University. This study was a qualitative and quantitative study collecting data by interviewing 9 executive and specialist Public Relation Officers and distributing questionnaires for 161 Public Relation Officers. The results could be summarized as follows: 1) The competency level of Public Relation Officers, Chiang Mai University revealed that all aspects were found at high level. The core competency of Public Relation Officers, Chiang Mai University comprised knowledge, skills and attribute were found at high level and the functional competency of human relations, self-control and personality, and Public Relation knowledge and skill were at a high level. 2) The essential competency framework of Public Relation Officers, Chiang Mai University consists of personality of human relations, knowledge, skill, and self-control and personality respectively. 3) The guidelines of applying the competency concept for Public Relation Officers, Chiang Mai University found that appropriate to used competency in Public Relation Officers. First, for recruitment selection and assignment, second for personnel development, and lastly for employee assessment.