The most important factor affecting the choice of employers when establishing a employment relationship is the professional background of the employee. The employees present this information to the employer with the application file. Undoubtedly, the effect of a third person, especially a former employer, regarding the professional background of the employee is more effective than the assumption that it is objective. This is often accomplished by a reference letter from the previous employer or supervisor. In our legal order, although employers are not obliged to issue a reference letter, it is foreseen to arrange a certificate of employment that creates a reference letter effect. The document has been subjected to various classifications in the doctrine. The content of the document constitutes the criterion of one of these classifications. Although the legal basis of the certificate of employment includes general information about the content, the elements that should be included in the content need to be detailed. Since this debt of the employer is not known much by the employees, the issue has not been moved to the judicial decisions within the framework it should be. In our study, although partly information about what the working document is, it is tried to examine mainly its content.