Living organisms commonly harbour endosymbiotic bacteria within their cells, which can have a significant impact on the host's biology and evolution. Among these endosymbionts, Wolbachia and Rickettsia have been identified as widespread bacteria that associate with various eukaryotic hosts, including invertebrates such as insects. However, our understanding of the distribution and transmission of these endosymbionts among different insect species remains inadequate. Therefore, this research aims to conduct a preliminary survey to investigate the prevalence of the both endosymbiotic bacteria in insect populations in Nakhon Pathom province. The screening was performed using PCR assays with specific DNA primers for both Wolbachia and Rickettsia. The observation of 113 insect individuals, representing 4 insect orders, i.e., Hymenoptera, Lepidoptera, Coleoptera and Diptera, and classified as 20 species. Four species were found to be positive for Wolbachia, i.e., Monomorium sp., Leptosia nina, Junonia lemonias and Megaselia scalaris. However, Rickettsia was detected in Culex sp. and M. scalaris. The findings from this research will be used for further investigations into the strain-level of Wolbachia and Rickettsia, to better understand the evolutionary relationships of these endosymbiotic bacteria. Additionally, these results may provide basic knowledge for narrowing down a particular insect group to study the distribution of endosymbiotic bacteria that are more specific to certain insect taxa.