Safety is one of the most important factor for the commercialization of UAM. It is necessary to increase the reliability of the aircraft system by setting a quantitative safety target level, identifying potential hazards, and allocating redundancy and reliability level of system to meet the safety target through a safety assessment. The UAM aircraft to be operated for transportation over the urban area will be expected to be an eVTOL type aircraft, and it is characterized by distributed electric propulsion, automated powered lift/control system and transition flight. In this study, through the safety assessment case study of OPPAV, an UAM technology demonstrator, the eVTOL safety assessment characteristics and considerations are presented.