A cleaning device capable of cleaning a surface of a conveyance roller that conveys a sheet in an image forming apparatus, the cleaning device comprising: a cleaning unit including: a cleaning part having a contact surface extending along an axial direction of the conveyance roller, the contact surface being brought into contact with the surface of the conveyance roller to clean the surface of the conveyance roller; and a housing that supports the cleaning part, wherein the cleaning part includes: a web of a strip shape, the web forming the contact surface that comes in contact with the conveyance roller; a pressing roller that presses the web against the conveyance roller; a feed-out roller that feeds out the web so as to cause a part of the web that comes in contact with the conveyance roller to shift; and a take-up roller that takes up the web, and the housing has a box structure having an opening that receives foreign matter (Ta, Tc) dropping from a vicinity of a nip portion formed between the pressing roller and the conveyance roller, wherein the housing includes: a pair of wall portions (701,702) that support both ends of respective roller shafts of the pressing roller, the feed-out roller, and the take-up roller; a bottom wall disposed below the cleaning part; and a sheet member disposed so as to face a nip portion between the pressing roller and the conveyance roller across the opening, the sheet member, together with the pair of wall portions (701,702) and the bottom wall, jointly forming the box structure, characterized in that the sheet member is attached to the bottom wall so as to extend upward, and has a lower part with predetermined first rigidity and an upper part with second rigidity lower than the first rigidity, and the opening is formed between the pressing roller and an upper edge of the upper part. a cleaning part having a contact surface extending along an axial direction of the conveyance roller, the contact surface being brought into contact with the surface of the conveyance roller to clean the surface of the conveyance roller; and a housing that supports the cleaning part, wherein the cleaning part includes: a web of a strip shape, the web forming the contact surface that comes in contact with the conveyance roller; a pressing roller that presses the web against the conveyance roller; a feed-out roller that feeds out the web so as to cause a part of the web that comes in contact with the conveyance roller to shift; and a take-up roller that takes up the web, and a web of a strip shape, the web forming the contact surface that comes in contact with the conveyance roller; a pressing roller that presses the web against the conveyance roller; a feed-out roller that feeds out the web so as to cause a part of the web that comes in contact with the conveyance roller to shift; and a take-up roller that takes up the web, and the housing has a box structure having an opening that receives foreign matter (Ta, Tc) dropping from a vicinity of a nip portion formed between the pressing roller and the conveyance roller, wherein the housing includes: a pair of wall portions (701,702) that support both ends of respective roller shafts of the pressing roller, the feed-out roller, and the take-up roller; a bottom wall disposed below the cleaning part; and a sheet member disposed so as to face a nip portion between the pressing roller and the conveyance roller across the opening, the sheet member, together with the pair of wall portions (701,702) and the bottom wall, jointly forming the box structure, characterized in that the sheet member is attached to the bottom wall so as to extend upward, and has a lower part with predetermined first rigidity and an upper part with second rigidity lower than the first rigidity, and the opening is formed between the pressing roller and an upper edge of the upper part.