A development device includes a development casing for containing two-component developer, a developer bearer, a developer regulator to adjust an amount of developer carried on the developer bearer, a first developer conveyance member to supply developer to the developer bearer, a second developer conveyance member to transport axially developer separated from the developer bearer, first and second conveyance channels divided by a partition, in which the first and second developer conveyance members are respectively provided, and a removable sheet member to cover the developer bearer in an area facing the developer regulator, the first and second conveyance channels, and the partition. A first end portion of the sheet member extends from the second conveyance channel outside the development casing through a through hole formed in the development casing, and a second end portion thereof is retained by a retainer at a position outside the developer regulator.