The aim of this study was to analyse the determining factors behind parents' and students' decisions when choosing upper-secondary schools in Japan and how these factors were affected by the implementation of the new "Free High School Tuition" law introduced in 2010. Public and private upper-secondary schools can be either vocational or academic. This school choice was analysed using the characteristics of families and schools included in the PISA 2009 and 2012 questionnaires in a multinomial logit model. The most influential family characteristics in the upper secondary school choice in Japan are related to the family budget, parental education, class, and status. Moreover, the results show that the implementation of the new law affected families' school choice. Nevertheless, the law did not have the same equalising effect on families with more than one child and low-budget families in areas with a limited offer of private schools.