Since the Fukushima disaster, medical professionals have been involved in risk communication with residents affected. This is an urgent issue, and an important aspect of global disaster preparedness is defining the essential characteristics of professional risk communication, and training medical professionals and students to conduct effective risk communication. Using a narrative of risk trade-offs between radionuclides in the diet and traffic accidents as an example, we introduce the seven essential characteristics required by medical professionals and authorities involved in risk communication: (1) risk assessment, (2) differentiating between risk acceptance and risk trade-offs, (3) understanding differences in risk quality, (4) understanding how to frame information given residents' values, (5) giving attention to coping with too-high risk, (6) building trust and (7) fully considering how information is provided. Furthermore, we introduce an example of lectures at which participants can voluntarily learn the seven essential characteristics of risk communication through group discussions.