An image reading device comprising: a document feeding device configured to convey a document along a predetermined conveyance path such that the document passes over an upper side of a platen glass; a light source that is provided at a lower side of the platen glass, configured to irradiate light to the document; an image forming lens configured to form an image of reflected light reflected in the document; a plurality of line sensors (33r, 33g, 33b) configured to receive reflected light of color component that has passed through the image forming lens and is different from one another to output as image signals; and a position shift correction unit configured to correct position shifts between the image signals outputted from the plurality of line sensors, wherein, a line through which the reflected light of each color component reflected in the document and incident to each line sensor (33r, 33g, 33b) passes on the upper surface of the platen glass is defined as a reading line (Lr, Lg, Lb) corresponding to each line sensor (33r, 33g, 33b), heights from the reading lines (Lr, Lg, Lb) on the upper surface of the platen glass corresponding to the line sensors (33r, 33g, 33b) to the predetermined conveyance path are employed as reading heights of the line sensors (33r, 33g, 33b) and the position shift correction unit is configured to perform first correction control for correcting the position shifts between the image signals outputted from the line sensors (33r, 33g, 33b) on a basis of a difference of the reading heights (ΔHrg, ΔHbg) of the line sensors (33r, 33g, 33b), characterised in that the image reading device further comprises: a document conveyance angle detection member provided so as to abut a part of an upper surface of the document at a time of start of conveyance of the document by the document feeding device; a support shaft extending in the main scanning direction and supporting the document conveyance angle detection member so as to be swingable, an angle detection sensor configured to detect a rotation angle of the document conveyance angle detection member around the support shaft, wherein the document conveyance angle detection member is configured to be pressed upward by the document and to rotate upward around the support shaft when the conveyance of the document is started by the document feeding device, and the first correction control by the position shift correction unit is control for calculating a conveyance angle of the document based on a rotation angle of the document conveyance angle detection member and calculating the difference of the reading heights (ΔHrg, ΔHbg) of the line sensors (33r, 33g, 33b) based on the calculated conveyance angle of the document and positions of the reading lines on the upper surface of the platen glass corresponding to the line sensors (33r, 33g, 33b). a document feeding device configured to convey a document along a predetermined conveyance path such that the document passes over an upper side of a platen glass; a light source that is provided at a lower side of the platen glass, configured to irradiate light to the document; an image forming lens configured to form an image of reflected light reflected in the document; a plurality of line sensors (33r, 33g, 33b) configured to receive reflected light of color component that has passed through the image forming lens and is different from one another to output as image signals; and a position shift correction unit configured to correct position shifts between the image signals outputted from the plurality of line sensors, wherein, a line through which the reflected light of each color component reflected in the document and incident to each line sensor (33r, 33g, 33b) passes on the upper surface of the platen glass is defined as a reading line (Lr, Lg, Lb) corresponding to each line sensor (33r, 33g, 33b), heights from the reading lines (Lr, Lg, Lb) on the upper surface of the platen glass corresponding to the line sensors (33r, 33g, 33b) to the predetermined conveyance path are employed as reading heights of the line sensors (33r, 33g, 33b) and the position shift correction unit is configured to perform first correction control for correcting the position shifts between the image signals outputted from the line sensors (33r, 33g, 33b) on a basis of a difference of the reading heights (ΔHrg, ΔHbg) of the line sensors (33r, 33g, 33b), characterised in that the image reading device further comprises: a document conveyance angle detection member provided so as to abut a part of an upper surface of the document at a time of start of conveyance of the document by the document feeding device; a support shaft extending in the main scanning direction and supporting the document conveyance angle detection member so as to be swingable, an angle detection sensor configured to detect a rotation angle of the document conveyance angle detection member around the support shaft, wherein the document conveyance angle detection member is configured to be pressed upward by the document and to rotate upward around the support shaft when the conveyance of the document is started by the document feeding device, and the first correction control by the position shift correction unit is control for calculating a conveyance angle of the document based on a rotation angle of the document conveyance angle detection member and calculating the difference of the reading heights (ΔHrg, ΔHbg) of the line sensors (33r, 33g, 33b) based on the calculated conveyance angle of the document and positions of the reading lines on the upper surface of the platen glass corresponding to the line sensors (33r, 33g, 33b).