Provided is a can asperity detection device which does not need an additional conveyance device for inspection, suppresses increased inspection costs, and allows for quick detection of defective merchandise while the defective merchandise is being conveyed. The can asperity detection device is provided with a first lighting means (30) for irradiating from the side of the can (20) a first illuminating light substantially horizontal to the upper surface (21a) of the ferrule part (21), a second lighting means (40) for irradiating from above the can (20), a second illuminating light substantially perpendicular to the upper surface (21a) of the ferrule part (21), and an imaging device (50) arranged above the can (20), photographing the upper surface (21a) of the ferrule part (21) and detecting the reflected light from the upper surface (21a). At least three or more first lighting means (30) are arranged at substantially equal distances in the circumferential direction around the periphery of the ferrule part (21). The first illuminating light irradiated from each of the lighting means (30) is irradiated such that each optical axis is substantially horizontal to a direction that runs from the lateral to upper surface (21a) of the ferrule part (21), and the respective optical axes are not aligned with each other, so as to conform to the cylindrical surface tangent direction of the ferrule part (21).