Provided is an asperity detection device for a can which does not need an additional conveyance device for inspection, reduces increased inspection costs, and allows for quick detection of defective merchandise while conveying the can.The asperity detection device for a can is provided with: first lighting devices (30) which irradiate a first light substantially horizontal to a top surface (21a) of a mouth section (21) from a side of a can (20); a second lighting device (40) which irradiates a second light substantially vertical to the top surface (21a) of the mouth section (21) from above the can (20); and an imaging device (50) which is arranged above the can (20), photographs the top surface (21a) of the mouth section (21), and detects reflection at the top surface (21a), in which at least three or more first lighting devices (30) are arranged with substantially even intervals in a circumferential direction around a periphery of the mouth section (21), the first light which is irradiated from each of the first lighting devices (30) is irradiated to the top surface (21a) from a side of the mouth section (21) along a tangent line of a cylindrical surface of the mouth section (21) substantially horizontal so that an optical axis is not coincide with the optical axes of the other first lights.