Background: Adolescent is a transition period from childhood to adulthood, seeking self-identity, anti-social behavior, violence and substance use. Parenting style is one of the risk factors determining substance use behavior among adolescents to prevent and overcome this behavior's consequences. This study aims to determine the relationship between parenting style toward substance use among adolescents in Denpasar. Methods: This research is an analytic observational study with a case-control study design. This research sample is adolescent drug users aged 12-25 years who live with their parents aged 0-17 years. The study was carried out in/at the Class IIA Kerobokan Denpasar Prison from August 2020 to September 2020. The data sources are primary data that taken from the PSQ (Parenting Style Questionnaire) and WHO-ASSIST questionnaires. The independent variable is the parenting style, while the dependent variable is the level of substance use. The data were/are analyzed using the chi-square/Fisher exact test with p-value of <0.05 is considered as significant. Result: The results show that there is a significant relationship between unexpected parenting style according to parents/guardians and drug abuse among adolescents (r = 0.34; p <0.05) and that increased the risk of moderate-heavy drug use among adolescents (OR = 5.93; 95% CI = 1.362-25.788; p = 0.011). Conclusions: Unexpected parenting style is associated to/with higher levels of substance use due to guilt, abusive parenting, neglect, which lead to negative self-esteem in children, emotional submission, insecurity and a lack of self-control in children.