When Buddhism came to Thailand, it caused a great change in traditional beliefs. The Buddhist Philosophy of Buddhism merges with the traditional Thai belief which is the mysterious belief. Especially, the belief in the Ancestral Spirits which is an important belief in the past. Buddhist Philosophy has transformed Thai society into a society of making merit in order to go to heaven and escape from hell after passing away from human life. Ancestral Spirits and mystical beliefs also benefit from Buddhist Philosophy in the origin and emergence of Ancestral Spirits and mystical beliefs.And another belief that has been greatly influenced by Buddhism is the belief in gratitude because it also conforms to the principles of Buddhism.However, Thai people do not fully understand Buddhist Philosophy.Therefore,all beliefs are so intertwined that they cannot be separated from each other