Generation Z has started entering adulthood and the workplace in the last couple of years. Both generations Y and Z will be a major force in workplace as well as marketforce. Both generations shared similar characteristics, e.g. digital naïve, constant connection online, high confidence, and demanding. However, they are born and raised in different economic and life situation. Those differences will affect the beliefs, behaviors, and values. Understanding this will help companies and other organizations who work to tackle the environmental issue on how to approach and ensure their participation. At present, there are still limited studies to see the difference between both generations' characteristics. This study aims to see whether there are differences in concern on the environmental issue between groups. A descriptive quantitative study was conducted in generation Y and Z in Indonesia. Samples were collected using snowball methods. Four-point Likert scale questionnaires were designed and distributed. The questionnaires collected and eligible to be analyzed was 140. The result shows there are no significant differences in the concern of the environment, participate in reducing plastic use, and the opinion of the importance of a company to have a sustainability development program. However, there is significantly different in actively participating in an event promoting environmental issues. This study contributes to the body of evidence on Generation Y and Z characteristics.