A method of manufacturing a developer container including a frame configured to define a developer containing portion, a first electrode, and a second electrode arranged on a surface of the frame and having a surface opposed to the first electrode, a developer amount in the developer containing portion being detected based on a capacitance between the first electrode and the second electrode, the method including: holding a conductive resin member constituting the second electrode on a mold configured to mold the frame, a surface of the conductive resin member being in contact with a surface of the mold configured to mold a surface of the frame on a side of the developer containing portion; injecting a resin to be formed into the frame, into the mold on which the conductive resin member is held; and curing the resin to form the frame to which the second electrode is fixed.