The risk of data theft is still a negative impact of smartphone technology development that harms its users. One cause of data theft is information security behavior. Therefore, this study was conducted to determine information security behavior and its differences among smartphone users in Indonesia based on the demographic variables (i.e., gender, generation, educational background, and operating system) and four approaches, namely Avoiding Harmful Behavior, Settings, and Add-on Utilities, Preventive Behavior, and Disaster/Data Recovery. The data obtained from 400 respondents were processed using Pearson's chi-square and post hoc tests. The results showed that there are significant differences between the demographic variables and approaches. It was revealed that men behave better than women in terms of adopting settings and add-on utilities, preventive behavior, and disaster/data recovery. On the other hand, men tend to have riskier behavior than women in avoiding harmful behavior. Based on generation, it was found that Generation Z exhibits more secure behavior than Generation Y in terms of settings and add-on utilities regarding remote device locking. Meanwhile, Generation Z has better behavior than Generations X and Y in preventive behavior as they uninstall/remove unused applications. Furthermore, undergraduate users behave better than high schoolers in avoiding harmful behaviors such as sharing PIN/passwords. Lastly, iOS users were found to have better data recovery behavior than Android users in automatically backing up data in the cloud. These results can be considered when designing security education, training, and awareness programs to improve information security.