Migration is most fundamental to the understanding of continuously changing space content and space relationship of an area. Migrants tend to move from areas of lower economic opportunity to those of higher economic opportunity. The internal migration is a very important component in the population structure of Arunachal Pradesh. Migration has important economic consequences on employment and unemployment for both the emigrant and immigrant while emigration tends to reduce unemployment and immigrating tends to expand unemployment. Migration is most fundamental to the understanding of continuously changing space content and space relationship of an area. The trends in migration have also been considered as a sensitive index of changing pattern of economic opportunities as well as urbanization in an area. The objective of the study is to find out the causes and effects of migration in Arunachal Pradesh. This study is an introspective type of research based on secondary data gathered from books, articles, websites, web-based journals, Census Reports and government offices.