It's possible to look at the both sides of Islam's acceptance of local folk beliefs & rituals, and indigenous religion's acceptance of Islamic doctrines in the acculturation process between indigenous religion and Islam in Javan society. It can be said that from the standpoint of the Sufis who achieved great exploits in propagating Islam into Javan society, they accepted the Javan traditional practice, which has been upheld by Javans, in order to get Islam to take root in all areas of Java while from the viewpoint of the vast majority of lower classes who have pursued spiritism and dynamism, their indigenous religion adopted the form of accepting Islam. Much of the evidence indicating the use of folk beliefs mixed with Islam and co-existence of both religions can be seen through the habit and rites projected onto their daily living. The representative ritual is selamatan called "kenduri.'Selamatan is a ritual in which participants perform ancestral rites, such as giving prayers by preparing food with their utmost sincerity, and share food with their relatives and neighbors. Particularly, the rituals performed in time of memorial services are observed by almost all groups in Java. Generally, the rituals are guided by the employees at masjid who are skilled in reciting Qur'an called modin. Javans' ancestral worshipping is amazingly big, and they believe in not only the fact that the performance of selamatan can make ancestors' souls in after life peaceful but they also believe in the fact that those souls of ancestors bring prosperity to their descendants. This writer, under the perception that Islamic mysticism and sufism have become Javan(ized) through being grafted onto Javan mysticism in the process of their propagation and taking root in Javan society, has a shot at casting light on the transformation process. For this purpose, this study attempts to shed light on the process of kejawen's being naturalized to Javan society after looking into the main idea of the two sufisms prevailing in Javan society including snnni sufism and philosophical sufism. Next, this study is going to consider their view of religion through the rite of passage, which have the most important weight in daily life of Javan society among several cases of rite naturalization, especially birth, wedding ceremony, funeral ceremony, and ancestral rites, etc. Such work could be a measure to weigh up to what extent Islam has been transformed in the process of being naturalized to Javan society. In conclusion, this study is going to examine the aspect and the present status of the kejawen stratum's being collectivized.