A developer case that contains developer and supplies the developer to another device in a specified replenishing position, the developer case comprising: a case main body that includes a bottom wall, a top wall, and a first side wall and a second side wall that connect end portions of the bottom wall to corresponding end portions of the top wall; and a rotating unit disposed above the bottom wall in the case main body, the rotating unit transporting the developer, the rotating unit including a rotation shaft that extends in a direction in which the bottom wall extends, a transportation member disposed in an outer circumference of the rotation shaft, the transportation member rotating together with the rotation shaft, and a drive input member to which a drive force that rotates the rotation shaft in a specified rotation direction about an axis is inputted, wherein, in a section perpendicular to the rotation shaft, the bottom wall has an inner surface having a semi-circular shape corresponding to a locus of rotation of a radially furthest protruding portion of the transportation member, and the first side wall and the second side wall respectively have a first linear inner surface and a second linear inner surface, the first linear inner surface and the second linear inner surface linearly extending in an up-down direction; the first linear inner surface and the second linear inner surface each extend upward along a tangent line of the semi-circular inner surface of the bottom wall in a straight line from the bottom wall toward the top wall; the first side wall is positioned on an upstream side in a rotation direction of the rotating unit, the second side wall is positioned on a downstream side in the rotation direction of the rotating unit, and a distance between the first linear inner surface and the second linear inner surface increases from the bottom wall side toward the top wall; characterized in that when the developer case is in the replenishing position, in a case where a line perpendicular to a horizontal line that passes through the axis of the rotation shaft is defined as a reference line, a first angle θ1 formed between the reference line and the first linear inner surface is smaller than a second angle θ2 formed between the reference line and the second linear inner surface. a case main body that includes a bottom wall, a top wall, and a first side wall and a second side wall that connect end portions of the bottom wall to corresponding end portions of the top wall; and a bottom wall, a top wall, and a first side wall and a second side wall that connect end portions of the bottom wall to corresponding end portions of the top wall; and a rotating unit disposed above the bottom wall in the case main body, the rotating unit transporting the developer, the rotating unit including a rotation shaft that extends in a direction in which the bottom wall extends, a transportation member disposed in an outer circumference of the rotation shaft, the transportation member rotating together with the rotation shaft, and a drive input member to which a drive force that rotates the rotation shaft in a specified rotation direction about an axis is inputted, a rotation shaft that extends in a direction in which the bottom wall extends, a transportation member disposed in an outer circumference of the rotation shaft, the transportation member rotating together with the rotation shaft, and a drive input member to which a drive force that rotates the rotation shaft in a specified rotation direction about an axis is inputted, wherein, in a section perpendicular to the rotation shaft, the bottom wall has an inner surface having a semi-circular shape corresponding to a locus of rotation of a radially furthest protruding portion of the transportation member, and the first side wall and the second side wall respectively have a first linear inner surface and a second linear inner surface, the first linear inner surface and the second linear inner surface linearly extending in an up-down direction; the first linear inner surface and the second linear inner surface each extend upward along a tangent line of the semi-circular inner surface of the bottom wall in a straight line from the bottom wall toward the top wall; the first side wall is positioned on an upstream side in a rotation direction of the rotating unit, the second side wall is positioned on a downstream side in the rotation direction of the rotating unit, and a distance between the first linear inner surface and the second linear inner surface increases from the bottom wall side toward the top wall; the bottom wall has an inner surface having a semi-circular shape corresponding to a locus of rotation of a radially furthest protruding portion of the transportation member, and the first side wall and the second side wall respectively have a first linear inner surface and a second linear inner surface, the first linear inner surface and the second linear inner surface linearly extending in an up-down direction; the first linear inner surface and the second linear inner surface each extend upward along a tangent line of the semi-circular inner surface of the bottom wall in a straight line from the bottom wall toward the top wall; the first side wall is positioned on an upstream side in a rotation direction of the rotating unit, the second side wall is positioned on a downstream side in the rotation direction of the rotating unit, and a distance between the first linear inner surface and the second linear inner surface increases from the bottom wall side toward the top wall;