This brief report documents the results of a survey that measured the public’s and doctors’ perceived effectiveness of preventive behaviors against COVID-19, in Japan. Medical doctors ( n = 117) and the general public ( n = 1086) participated in our online survey. The results of the analysis of mean scores indicate that there were only slight differences in perceived effectiveness between the two groups, while the differences in distributions were remarkable. The results of Silverman’s test suggest the unimodality of doctors’ responses and multimodality of the public’s responses. Implications of the findings to combat the risk of infection are discussed.