Koshima islet, where all the Japanese macaques have been identified for over sixty years, is well-known as birthplace of primatology in Japan. Unique data such as maternal lineage and monthly body weight data has been accumulated for long term. While body weight is one of important indexes which affect animals’ survival and reproductive performance, it’s almost impossible to measure it in field. In my analysis female infants grown slowly give birth to less offspring than ones grown fast due to shorter life span and longer interbirth interval. Males grown slowly also suffer disadvantage in survival and related index, lifespan and maximum body weight in whole life time. So infants which are behind in growth may be going to pay in their adulthood.