This study aims to prove the effect of firm size, leverage and investment decisions on firm value as the dependent variable empirically. The sample in this study were companies listed in the Jakarta Islamic Index 2015-2019 using the purposive sampling method. The data analysis technique used is multiple linear regression analysis with the SPSS 23 test tool. This study indicates that firm size and investment decisions have a positive effect on firm value, while leverage has a negative effect on firm value.