The background to this research found indications that the principal's leadership was not optimal, the effectiveness of the principal's leadership which was expected to provide enthusiasm for teachers to improve teacher performance was in fact only limited to a program, but was not implemented by the principal. So, what the school should achieve through the leadership of the principal as 1) Manager, 2) Supervisor, 3) School Administrator cannot be appropriate and run effectively. This research aims to determine the effectiveness of school principal leadership in improving teacher performance through organizational culture. The method used in this research is a qualitative approach to phenomenological studies. The informants in this research were the Principals of Elementary Schools in the Ki Hajar Dewantara Cluster, Adipala District, Cilacap Regency, totaling 5 Principals. Data collection techniques use interviews, observation and documentation studies. Activities in data analysis are data reduction, data presentation, and drawing conclusions. The research results show that a communicative and inspiring principal can increase staff commitment and performance through several approaches, such as special meetings at the beginning of the semester and staff meetings to discuss the school's vision and mission. According to Devi (2021), this approach keeps shared goals in mind by staff and strengthens the sense of belonging. This approach has been proven to increase staff commitment and performance, with staff feeling more involved and responsible in achieving school goals, showing better work morale and performance (Sari, 2021). This success highlights the important role of leadership in directing and motivating staff. Supporting factors to improve teacher performance through work organizational culture at Gugus Ki Hajar Dewantara Elementary School, Adipala District, Cilacap Regency, namely open communication; coaching and development; collaboration and teamwork; awards and recognition. The inhibiting factors in improving teacher performance through organizational culture in elementary schools in the Ki Hajar Dewantara cluster, Adipala sub-district, Cilacap district, are policy changes; inadequate work facilities and work environment; absence of constructive evaluation and feedback.