Amid the trend of globalization, there are impacts that result in rapid social and cultural changes, and there is clear diversity. The issue of intangible cultural heritage is a challenge for the cultural management of the countries in Southeast Asia in order to achieve sustainabilty and allow intangible cultural heritage to be able to continue to exist during this era of abrupt change. This study aims to present the defining and the classification of intangible cultural heritage of the group of countries in Southeast Asia in order to pave the way for the creation of the registration of an overall list of representatives of the intangible cultural heritage of humanity. For this research study using qualitative methods, data was collected from a documentary study together with in-depth interviews from a group of key informants totaling 30 people, and data analysis with content analysis of the results of the study indicated that defining intangible cultural heritage can be divided into two types, which are definition according to the designation of social institutions in countries and definition according to the perception of people in the social context of each country. Thus, the classification of intangible cultural heritage is based on the social and cultural context of each country.