A developing device comprising a housing and a developer carrier, which is carrying developer,
- wherein the housing comprises a first frame and a second frame that is welded to the first frame,
- wherein the first frame comprises:
- a sidewall, which is configured by a pair of the sidewalls that face each other with an interval in a longitudinal direction of the developer carrier therebetween,
- wherein the sidewall extends in a direction perpendicular to the longitudinal direction and in a direction from the first frame to the second frame, wherein a orthogonal direction is perpendicular to both the longitudinal direction and the extending direction, and wherein each of three direction has a first side and a second side that is opposite to the first side;
- a connection wall configured to be open at both a first side in the extending direction at the sidewalls and a first side in the orthogonal direction at the sidewalls,
- wherein the connection wall connects a second side end portion in the extending direction at the sidewall and connects a second side end portion in the orthogonal direction at the sidewall, wherein the first frame includes:
- a first welding surface that is to be welded to the second frame, wherein the first welding surface is configured to extend to a first side end portion in the orthogonal direction at the sidewall and is continuously formed on a first side end surface in the extending direction at the sidewalls and a first side end surface in the extending direction at the connection wall that connects the second side end portion in the orthogonal direction at the sidewall;
- and
- a first adhesion surface that is continuously formed with a first side end portion in the orthogonal direction at the first welding surface, wherein the first adhesion surface extends in the extending direction and is opposite to the developer carrier in the orthogonal direction, wherein the second frame includes:
- a second welding surface that is formed to correspond to the first welding surface and is to be welded to the first welding surface;
- and
- a second adhesion surface that is continuously formed with a first side end portion in the orthogonal direction at the second welding surface, and wherein the second adhesion surface is substantially flush with the first adhesion surface when the second frame is welded to the first frame, and
- wherein the first frame and the second frame are welded so that the first welding surface and the second welding surface are opposite to each other in the extending direction, and
- wherein the developing device further comprising:
- a seal member that is adhered to the first adhesion surface and the second adhesion surface, wherein the seal member covers a first side end portion from the first side in the orthogonal direction at an opposite part where the first welding surface and the second welding surface are disposed opposite one another;
- and
- a filling agent that is filled between the seal member and the first side end portion in the orthogonal direction at the opposite part.