Life satisfaction instrument among psychology related analyses has weaknesses in terms of gender bias testing especially among adolescents. Therefore this research aims to develop and validate a life satisfaction instrument in the Indonesian language which is new and undetected by gender bias. The modern construct-oriented scale construction method was selected as a guide in developing the instrument and the participants were 474 adolescents from various cities in Indonesia. At the initial screening stage using the Rasch model analysis 54 participants were detected as outliers hence further analysis was only conducted on 420. The results show that I-ALSS fulfills the assumptions of unidimensional and local independence with a good reliability score. Furthermore I-ALSS correctly categorizes answer choices into 8 items without detecting gender bias. Therefore it is a fairly good instrument to be used in Indonesia. PDF