The invention relates to a device for hardening nail varnish by ultraviolet radiation. The device comprises: a bearing surface (26) intended to support the hands or the feet of the user, radiation sources (38) able to emit a radiation to harden nail varnish in the form of a light beam to illuminate the nails of the user. The beams define on the bearing surface (26) at least six illuminated portions (42) separated from each other by a non-illuminated portion, with the number of illuminated portions (42) being less than nine.