The objectives of this research were: (1) to study the Buddhist ethics found in Theravada Buddhism, (2) to study the history of the folk songs of Nakhonsawan, and (3) to analyze the Buddhist ethics found in the folk songs of Nakhonsawan. This research applied the documentary research with collecting data from Tipitaka, academic textbooks, related documents and researches. Analysis of the data used the analysis of the content and the summary of the research used presenting the descriptive results of the research.

The results showed that

1. The Buddhist ethics found in Theravada Buddhism were divided into three categories: 1) the elementary level ethics: Penca-Sila (the Five Precepts), Lokapala (Virtues that protect the world),   Four Brahmavihara (the   Four sublime states of mind), Four Iddhipada (the Four Paths of Accomplishment), Six Disa (the Six direction) and Thirty-eight Mangala (the Thirty-eight   Blessings),   (2) the middle level ethics: Ten Kusalakammapatha (the Tenfold way of good action), and (3) the high level ethics: Atthangika-magga (the Noble Eightfold Path). 

2. The folk songs are the local cultural heritage that reflects the lifestyle of the community in the past. Nakhonsawan Province has suitable geography for the agriculture because the Chao Phraya River flows through Nakhonsawan Province. The majority of the population performs the agriculture. The lifestyle is simple. The people have close relationship, are generous, and have the unity. When doing the activities, the people helped to do the activities together until finishing. When the farming season arrived, the farmers gather together to help the farming. Meanwhile, the farmers sing a song together to relax from the farming. Then, these songs singing as a duet and the interacting each other become the folk songs of Nakhonsawan Province. The folk songs were divided into three categories: (1) Folk Dance songs, (2) Interactive songs, and (3) other theme songs.

3. Buddhist ethics in the Theravada Buddhism interfered in the folk songs were mostly the elementary level ethics: Penca-Sila (the Five Precepts), Lokapala (Virtues that protect the world),   Four Brahmavihara (the   Four sublime states of mind), Four Iddhipada (the Four Paths of Accomplishment), Six Disa (the Six direction) and Thirty-eight Mangala (the Thirty-eight   Blessings) because the the elementary level ethics is the basic ethics as the practice of the Buddhist, It makes everyone happy.