The Sambungmacan 1 fossil (Java, Indonesia) is assigned to the Homo erectus group. The carbonated matrix contained in this calvaria prevents the analysis of the internal surface. The CT data of the original fossil enables us to observe the conservation and mineralization state and the internal structures. Furthermore, we use the CT data to reconstruct the endocast, which shows that the morphological character of Sambungmacan 1 is close to the Ngandong hominids.