Regional development as an effort to improve human welfare always has an impact on the environment. Therefore, this research aims to determine stakeholder participation in Strategic Environmental Assessment (SEA) of Detailed Spatial Plan (DSP) for the Manokwari Regency Urban Area. The research was carried out from February to March 2021, where the research location in the Manokwari Urban Area which is the location for the delineation of DSP. Data collection was carried out by means of observation, interviews and secondary data studies. Observations were carried out directly during the discussion of SEA documents. The researcher describes in detail about the conditions in the field, human activities and the context in which the activities were held. Interviews were conducted by asking written questions to respondents and using prepared questionnaires. Data was analyzed using a stakeholder analysis approach to ensure aspects, including: a) determining precisely the parties that will be involved; b) guarantee the implementation of the principle of participation; c) guarantee that the results of the DSP document obtain public legitimacy; d) level of stakeholder participation. The research results show that the most dominant form of stakeholder participation is the contribution of input/suggestions and the provision of information/data from stakeholders. This means that there is a willingness and ability of the stakeholders involved to express their opinions scientifically. Stakeholders' willingness to participate can increase motivation to make changes, while the ability to participate is related to human resources and learning abilities.