This study was aimed to show the implementation of internal quality assurance system at Darul Hikam Islamic School. For this purpose, the researchers used qualitative methods, including analysis of documents, interviews and observations. The results indicated that quality assurance at Darul Hikam was prepared by Darul Hikam College independently, such as in planning, implementing, monitoring and evaluating. Program evaluation internal quality assurance in Darul Hikam, is conducted every semester and performance evaluation, the results of the evaluation are attached in the form of a work report card. The constraint faced by Darul Hikam is the mobility of teachers in and out of the human resources. To minimize the impact of teacher mobilization, Darul Hikam improved teacher's welfare and developed an intensive development package, because teachers and other human resources cannot adopt the system too long. So the human resources development team worked hard to develop new human resources and maintain the quality of the old human resources. Therefore, human resources and the guarantors of Internal Quality Assurance System should make program innovations to strengthen the quality assurance in Islamic School.