Jawa mosque is a 116-year-old mosque in the CBD of Bangkok. It is the center of the Thai-Muslim community of Javanese origin. The mosque needs to be conserved to keep the community’s identity and heritage, as a symbol of the existence of this ethnic minority in Thailand. This paper demonstrates how the style of the mosque is Javanese. The methodology is qualitative including ground research coupled with a literature review. First, ground research and site measurements are carried out to collect critical information for further analysis. Second, a literature review focuses on the theories on the origin of mosques in Java. Next, a comparative analysis between the Jawa mosque and the Javanese style mosque is carried out, followed by a result and discussion. Last, a conservation approach is discussed based on the significance of the building. The results of the comparative analysis show that the Jawa mosque meets 5 out of 6 distinct characteristics of the Javanese mosque as described in 1947 by Prof. G.F. Pijper, a Dutch historian from Leiden University: 1) the ground floor is square, 2) the roof is a pyramidal tiered-roof, 3) the platform is elevated, 4) there is a mihrab (niche) for prayer towards the Mecca city, and 5) there is a pendopo/serambi (front veranda) in the front and the balae (side veranda) for community gathering. This confirmation along with an analysis of the conservation approach based on the significance of the building - can be useful for further architectural conservation projects of the Jawa mosque. It can serve as a guideline or important architectural aspects to consider for further renovation and construction projects of the mosque.