This work examined the lifestyle of the Mon ethnic group residing in Wai Niaw Municipality, Thamaka District, Kanchanaburi Province, who had migrated from several villages in Ban Pong District, Ratchaburi Province, and settled in the municipality close to Mae Klong River more than 117 years ago. The study findings revealed that the livelihood of the ethnic group was based on neighborly cooperation and that agriculture was their main livelihood. They were hard-working and brought up their children to get more education for a better future. Some of their ethnic traditions and culture had been maintained, such as spirit appeasement rituals, spirit dance, ordinations, weddings, and funerals. However, their ethnic language had changed. It was found that only older generations were able to speak proficiently, while younger generations were unable to speak it at all. Furthermore, only the elderly continue to wear traditional dress, whereas young people had already begun to wear modern and fashionable clothes. The results of this investigation would be used as a guideline for maintaining the unique ethnic lifestyle.