A screw with a head; a shank extending axially and downwardly from said head, and including a leading end opposite to said head, and a thread unit extending helically around an axis of said shank; and at least one collecting groove that is disposed on said shank between said leading end and said head for collecting scraps and that does not criss-cross with crests of said thread unit; wherein said leading end has at least one flute to communicate with said at least one collecting groove; wherein said at least one collecting groove extends non-helically above said at least one flute, said at least one collecting groove defining a groove open end that faces in a radially outwards direction, a groove bottom wall opposite to said groove open end, and an upper groove boundary wall that extends from an upper end of said groove bottom wall to said groove open end and that extends around the axis of said shank in a non-helical manner; wherein said shank includes a portion with a circumferential surface which has a largest diameter of said shank except a crest diameter of said thread unit, said groove bottom wall of said least one collecting groove being deeper in a radial direction than said circumferential surface when measured from crests of said thread unit; wherein said shank further includes at least one grooved section extending circumferentially and having said at least one collecting groove, at least one upper section disposed between said at least one grooved section and said head, and a lower section disposed below said at least one grooved section and having said leading end; characterized in that said thread unit has a lower thread disposed at said lower section; and wherein said leading end is tapered and has a pointed tip, said lower thread extending helically toward said pointed tip of said leading end, said at least one flute extending across said lower thread and having a flute upper end that meets and communicates said at least one collecting groove and a flute lower end that meets said pointed tip, said flute upper end being larger than said flute lower end. a head; a shank extending axially and downwardly from said head, and including a leading end opposite to said head, and a thread unit extending helically around an axis of said shank; and at least one collecting groove that is disposed on said shank between said leading end and said head for collecting scraps and that does not criss-cross with crests of said thread unit; wherein said leading end has at least one flute to communicate with said at least one collecting groove; wherein said at least one collecting groove extends non-helically above said at least one flute, said at least one collecting groove defining a groove open end that faces in a radially outwards direction, a groove bottom wall opposite to said groove open end, and an upper groove boundary wall that extends from an upper end of said groove bottom wall to said groove open end and that extends around the axis of said shank in a non-helical manner; wherein said shank includes a portion with a circumferential surface which has a largest diameter of said shank except a crest diameter of said thread unit, said groove bottom wall of said least one collecting groove being deeper in a radial direction than said circumferential surface when measured from crests of said thread unit; wherein said shank further includes at least one grooved section extending circumferentially and having said at least one collecting groove, at least one upper section disposed between said at least one grooved section and said head, and a lower section disposed below said at least one grooved section and having said leading end; characterized in that said thread unit has a lower thread disposed at said lower section; and wherein said leading end is tapered and has a pointed tip, said lower thread extending helically toward said pointed tip of said leading end, said at least one flute extending across said lower thread and having a flute upper end that meets and communicates said at least one collecting groove and a flute lower end that meets said pointed tip, said flute upper end being larger than said flute lower end.