Currently, some Japanese women use a sanitary mask to hide their faces when not wearing makeup, perhaps because they believe that they are more attractive (or less ugly) when wearing a sanitary mask than when not wearing makeup. The present study examined the effect of wearing a sanitary mask on the perception of facial attractiveness. We manipulated the presence or absence of a mask in the main experiments or an occluder (e.g., notebook) in control experiments and asked participants to rate facial images. The results revealed that attractive faces wearing a sanitary mask were perceived as less attractive than the same faces without the mask, contrary to Japanese women's belief. This is the first study to demonstrate a new phenomenon, the sanitary‐mask effect, in which observers underestimate the physical attractiveness of a mask‐wearing face. Importantly, the pattern of the results of perceived attractiveness was substantially altered when a control object occluded the faces. This suggests that facial occlusion by a sanitary mask has a unique effect, due to occlusion and unhealthiness priming.