The purposes of the study of “The Role of Chiangmai Province Office of Labour Protection and Welfare in the Management of Labour’s Complaints, 2555 B.E.” were to investigate the causes of labour’s complaints in Chiang Mai in 2555 B.E., to analyze and classify labour’s complaints, as well as to study the procedure and the result of the management of labour’s complaints. Data was analyzed through conceptual framework of labour relations, labour law, conciliation and mediation principles. This independent study is a qualitative research which data have been collected from documentary sources and in-depth interview with the Labour Inspectors of Chiangmai Province Office of Labour Protection and Welfare who are responsible for the management of labour’s complaints. The result of the study showed that the causes of conflict between employer and employee which lead to complaints at Chiangmai Province Office of Labour Protection and Welfare are “compensation”, consisting of basic pay, severance pay, overtime pay, holiday pay, commission, guarantee money and employee contribution. The procedure of the management of labour’s complaints comprises submission of complaints, investigation and consideration of complaints, and order issuance. In 2555 B.E., a total of 167 cases of complaints have been completed and 136 of 167 cases were terminated by conciliation method, which is the main principle of mediation between employer and employee while the Labour Inspectors are unprejudiced. This principle decreases the damage and violence that may be occurred as a result of conflicts. Moreover, the great number of terminated cases by conciliation method has diminished the number of litigation at the Labour Court. Therefore, the Chiangmai Province Office of Labour Protection and Welfare plays an important role not only in labour protection and welfare but also reduction of litigation before proceedings at the Labour Court.