An image forming apparatus comprising: an image bearing member adapted to bear a toner image; a transfer belt that is movable; and a transfer device (5, 50) adapted to transfer the toner image from the image bearing member to the transfer belt, the transfer device (5, 50) positioned on the opposite side of the transfer belt to the image bearing member, the transfer device (5, 50) including a brush member (5γ) having filament bundles (5ξ) each of which includes a plurality of conductive filaments (5ε) to contact the transfer belt and a holding portion(5β) on which the filament bundles (5ξ) arrayed, wherein among the filament bundles (5ξ) of the brush member(5γ), filament bundles (5ξ) located towards an upstream end of the brush member (5γ) in a moving direction of the transfer belt are formed as a weld portion located at the upstream end of the brush wherein the filament bundles (5ξ) located at the upstream end are welded along a plane orthogonal to the moving direction of the transfer belt onto the holding portion from tops of the filament bundles (5ξ) towards the holding portion(5β) such that welded filament bundles at the upstream end of the brush member (5γ) are rectilinear in the plane orthogonal to the moving direction of the transfer belt, or filament bundles (5ξ) located towards an upstream end of the brush member(5γ) in the moving direction of the transfer belt are cut along the plane orthogonal to the moving direction of the transfer belt such that the cut filament bundles at the upstream end of the brush member (5γ) are rectilinear in the plane orthogonal to the moving direction of the transfer belt. an image bearing member adapted to bear a toner image; a transfer belt that is movable; and a transfer device (5, 50) adapted to transfer the toner image from the image bearing member to the transfer belt, the transfer device (5, 50) positioned on the opposite side of the transfer belt to the image bearing member, the transfer device (5, 50) including a brush member (5γ) having filament bundles (5ξ) each of which includes a plurality of conductive filaments (5ε) to contact the transfer belt and a holding portion(5β) on which the filament bundles (5ξ) arrayed, wherein among the filament bundles (5ξ) of the brush member(5γ), filament bundles (5ξ) located towards an upstream end of the brush member (5γ) in a moving direction of the transfer belt are formed as a weld portion located at the upstream end of the brush wherein the filament bundles (5ξ) located at the upstream end are welded along a plane orthogonal to the moving direction of the transfer belt onto the holding portion from tops of the filament bundles (5ξ) towards the holding portion(5β) such that welded filament bundles at the upstream end of the brush member (5γ) are rectilinear in the plane orthogonal to the moving direction of the transfer belt, or filament bundles (5ξ) located towards an upstream end of the brush member(5γ) in the moving direction of the transfer belt are cut along the plane orthogonal to the moving direction of the transfer belt such that the cut filament bundles at the upstream end of the brush member (5γ) are rectilinear in the plane orthogonal to the moving direction of the transfer belt.