Understanding the idiocyncracies of various migration definitions constitutes basic prerequisites for migration research. The purpose of this paper is to compare the data of 'the last moves within five years' with those of 'residence five years earlier', and examine how these definitions differently delineate the same migrantions. The data used for the study stem from the Fourth Migration Survey, which was conducted in 1996 by the National Institute of Population and Social Security Research, Japan. Analyses show the following points; 1) Total number of migrants is larger in the 'last migration' data, since the data of 'residence five years earlier' cannot grasp those who moved out and returned to the same place within five years. 2) An examination by place of the previous residence reveals that as the distance of move increases, the number of migrants by 'residence five years earlier' rises relative to the one by 'last migration'. This tendency would be explained by the characteristics of multiple moves within five years. While the data differences between the two definitions are caused by multiple moves (including return migrations) within five years, distance patterns of these moves seem, as far as the present dataset is concerned, to be predominantly 'long-to-short' in their sequences. Since the data of 'residence five years earlier' grasp the earlier moves and 'the last move' data focus on the more recent, the former tend to outnumber the latter in the longer distance moves, and the vice versa in the shorter movements. 3) The above pattern of migration distance seems to be influenced by the lifecycle-related characteristics of migration, namely long-distance moves for educational advance or job search in the late teens or early 20s, followed by short-distance relocation for better housing. But this pattern is not necessarily observed among older migrants. 4) In term of reasons of move, higher percentages of 'residence with/near parents' and 'marriage/divorce' are observed in return migrations. Some other multiple moves also seem to show idiosyncrasies in their reasons and migrants' attributes. It could be concluded that the relationships between the migration indicators concerned would not remain constant but change in relation to temporal fluctuations in the trends of return migration, reasons of moves, and attributes of migrants, which are shaped by time-to-time socio-economic situations.
