A scanning device comprising: document feeding rollers (311/312/321/322/331) to convey a document along a document feeding path; a scanning member provided on the document feeding path to read images from the document; a cover to open and close a part of the document feeding path; a knob to manually rotate at least one of the document feeding rollers (311/312/321/322/331); and a clutch unit (520/530) to selectively connect at least one of the document feeding rollers (311/312/321/322/331) to the knob in correspondence with opening and closing operations of the cover, wherein the clutch unit (520/530) is operable to disconnect the document feeding rollers (311/312/321/322/331) and the knob from each other when the cover is located at a closed position, and to connect at least one of the document feeding rollers (311/312/321/322/331) to the knob when the cover is located at an open position, characterised in that the clutch unit (520/530) comprises: a first clutch member provided on one of the document feeding rollers, and comprising a first connection portion; a second clutch member rotating with the knob, and comprising a second connection portion that is formed complementary with the first connection portion; and a sliding member to slide the second clutch member between a connecting position where the first and second connection portions (521/531) are connected to each other and a separation position where the first and second connection portions (521/531) are separated from each other, by the opening and closing operations of the cover. document feeding rollers (311/312/321/322/331) to convey a document along a document feeding path; a scanning member provided on the document feeding path to read images from the document; a cover to open and close a part of the document feeding path; a knob to manually rotate at least one of the document feeding rollers (311/312/321/322/331); and a clutch unit (520/530) to selectively connect at least one of the document feeding rollers (311/312/321/322/331) to the knob in correspondence with opening and closing operations of the cover, wherein the clutch unit (520/530) is operable to disconnect the document feeding rollers (311/312/321/322/331) and the knob from each other when the cover is located at a closed position, and to connect at least one of the document feeding rollers (311/312/321/322/331) to the knob when the cover is located at an open position, characterised in that the clutch unit (520/530) comprises: a first clutch member provided on one of the document feeding rollers, and comprising a first connection portion; a second clutch member rotating with the knob, and comprising a second connection portion that is formed complementary with the first connection portion; and a sliding member to slide the second clutch member between a connecting position where the first and second connection portions (521/531) are connected to each other and a separation position where the first and second connection portions (521/531) are separated from each other, by the opening and closing operations of the cover. a first clutch member provided on one of the document feeding rollers, and comprising a first connection portion; a second clutch member rotating with the knob, and comprising a second connection portion that is formed complementary with the first connection portion; and a sliding member to slide the second clutch member between a connecting position where the first and second connection portions (521/531) are connected to each other and a separation position where the first and second connection portions (521/531) are separated from each other, by the opening and closing operations of the cover.