High numbers of work accidents prove that work safety can no longer be denied. There must be a system to manage safety, especially in the construction sector, which has the highest contribution of work accidents in Indonesia. The system to manage safety is usually called Safety, Health, and Environment system (SHE system). However, the success of SHE systems is affected by the safety maturity level of the company. In fact, the number of work accidents is still increasing even though SHE systems have been applied in those companies. This research was conducted to develop a safety maturity model in order to improve safety and project performances. This research will draw a portrait of the existing safety maturity level of Indonesian construction companies. After knowing the existing level and the indicators that have not been fulfilled, a model for improving the existing safety maturity level was developed. The variables of the research are: safety policy, safety institution, safety cultures, safety maturity level, safety performance and project performance. This research was conducted through Delphi and questionnaire survey methods. The results of this research are the improvement of a safety maturity model and the suggestion of improvement actions to increase safety maturity level.