An image forming apparatus comprising: an image forming portion comprising: an image bearing member; a rotatable developer bearing member configured to bear developer comprising toner and carrier, and to convey the developer to a developing area facing the image bearing member; a regulating portion disposed to face the developer bearing member and configured to regulate an amount of the developer on the developer bearing member; a developing container comprising a first chamber configured to supply the developer to the developer bearing member, a second chamber which is disposed to face the developer bearing member and to which the developer passing the developing area is collected from the developer bearing member, and a partition wall configured to separate the first and second chambers (401 and 403), the developing container being configured to store the developer in such a manner that the developer circulates between the first and second chambers (401 and 403); a first conveyance screw disposed in the first chamber and configured to convey the developer in a first direction; and a second conveyance screw disposed in the second chamber and configured to convey the developer in a second direction opposite to the first direction; a first driving portion configured to rotatably drive the first and second conveyance screws (31 and 32); a second driving portion configured to rotatably drive the developer bearing member; and a controller configured to control the first and second driving portions (502 and 501), characterized in that the controller is configured to execute such a mode that in a first period in a non-image forming period in which an image forming operation by the image forming portion is not executed, the first and second conveyance screws (31 and 32) are rotatably driven by the first driving portion in a state in which the developer bearing member is not rotatably driven by the second driving portion, and in a second period, following the first period, in the non-image forming period, the developer bearing member is rotatably driven by the second driving portion in a state in which the first and second conveyance screws (31 and 32) are not rotatably driven by the first driving portion. an image forming portion comprising: an image bearing member; a rotatable developer bearing member configured to bear developer comprising toner and carrier, and to convey the developer to a developing area facing the image bearing member; a regulating portion disposed to face the developer bearing member and configured to regulate an amount of the developer on the developer bearing member; a developing container comprising a first chamber configured to supply the developer to the developer bearing member, a second chamber which is disposed to face the developer bearing member and to which the developer passing the developing area is collected from the developer bearing member, and a partition wall configured to separate the first and second chambers (401 and 403), the developing container being configured to store the developer in such a manner that the developer circulates between the first and second chambers (401 and 403); a first conveyance screw disposed in the first chamber and configured to convey the developer in a first direction; and a second conveyance screw disposed in the second chamber and configured to convey the developer in a second direction opposite to the first direction; an image bearing member; a rotatable developer bearing member configured to bear developer comprising toner and carrier, and to convey the developer to a developing area facing the image bearing member; a regulating portion disposed to face the developer bearing member and configured to regulate an amount of the developer on the developer bearing member; a developing container comprising a first chamber configured to supply the developer to the developer bearing member, a second chamber which is disposed to face the developer bearing member and to which the developer passing the developing area is collected from the developer bearing member, and a partition wall configured to separate the first and second chambers (401 and 403), the developing container being configured to store the developer in such a manner that the developer circulates between the first and second chambers (401 and 403); a first conveyance screw disposed in the first chamber and configured to convey the developer in a first direction; and a second conveyance screw disposed in the second chamber and configured to convey the developer in a second direction opposite to the first direction; a first driving portion configured to rotatably drive the first and second conveyance screws (31 and 32); a second driving portion configured to rotatably drive the developer bearing member; and a controller configured to control the first and second driving portions (502 and 501), characterized in that the controller is configured to execute such a mode that in a first period in a non-image forming period in which an image forming operation by the image forming portion is not executed, the first and second conveyance screws (31 and 32) are rotatably driven by the first driving portion in a state in which the developer bearing member is not rotatably driven by the second driving portion, and in a second period, following the first period, in the non-image forming period, the developer bearing member is rotatably driven by the second driving portion in a state in which the first and second conveyance screws (31 and 32) are not rotatably driven by the first driving portion.