This research aimed to know the relevance of pesantren Musthafawiyah Purba Baru against the regeneration of clerics in Mandailing Natal Regency. This was a qualitative research with the phenomenology approach. The research was conducted at Pesantren Musthafawiyah Purba Baru which had an address on Medan Padang Street, Purba Baru village, Lembah Sorik Marapi District, Mandailing Natal Regency in North Sumatera. The findings of the research showed that pesantren Musthafawiyah had two cultures. The first culture was a physical culture and the second one was a non physical culture. The clerics of Mandailing Natal had their own culture to play their roles in the middle of society.The physical culture such as abit (sarong), lobe (lebai), saroben (turban, solop (slippers) became one thing to be  maintained by the clercs. For finding out the activities of santri at pesantren Musthafawiyah, the researcher wrote the article about how the relevance of Pesantren Musthafawiyah Purba Baru culture was against cleric generation in Mandailing Natal Regency.