An image forming apparatus comprising: - a mounting portion (317, 327, 337, 347) to which a developer housing portion (316, 326, 336, 346) to house developer is mounted; - a lock mechanism (318, 328, 338, 348) configured to regulate attachment/removal of the developer housing portion (316, 326, 336, 346) mounted to the mounting portion (317, 327, 337, 347); - an image forming unit that is configured to form an image using the developer; - a first detection processing unit that is configured to detect a first state, the first state being a state where a remaining amount of the developer housed in the developer housing portion (316, 326, 336, 346) mounted to the mounting portion (317, 327, 337, 347) is less than a predetermined first reference amount; - a second detection processing unit that is configured to detect a second state, the second state being a state where the remaining amount of the developer housed in the developer housing portion (316, 326, 336, 346) mounted to the mounting portion (317, 327, 337, 347) is equal to or more than the first reference amount and less than a predetermined second reference amount, the second reference amount being larger than the first reference amount; - a first release processing unit that is configured to release the regulation on the attachment/removal of the developer housing portion (316, 326, 336, 346) by the lock mechanism (318, 328, 338, 348) when the first detection processing unit detects the first state; - a second release processing unit that is configured to release the regulation on the attachment/removal of the developer housing portion (316, 326, 336, 346) by the lock mechanism (318, 328, 338, 348) when the second detection processing unit detects the second state and a predetermined release condition is met; and characterized by - a display processing unit (54A, 54B) that causes a display to display a release operation screen when the second detection processing unit detects the second state while a door opening of a cover member is detected, the cover member being opened and closed to attach and remove the developer housing portion (316, 326, 336, 346), the release operation screen being used for a release operation of the regulation on the attachment/removal of the developer housing portion (316, 326, 336, 346) by the lock mechanism (318, 328, 338, 348), wherein the release condition includes an execution of the release operation in the release operation screen. - a mounting portion (317, 327, 337, 347) to which a developer housing portion (316, 326, 336, 346) to house developer is mounted; - a lock mechanism (318, 328, 338, 348) configured to regulate attachment/removal of the developer housing portion (316, 326, 336, 346) mounted to the mounting portion (317, 327, 337, 347); - an image forming unit that is configured to form an image using the developer; - a first detection processing unit that is configured to detect a first state, the first state being a state where a remaining amount of the developer housed in the developer housing portion (316, 326, 336, 346) mounted to the mounting portion (317, 327, 337, 347) is less than a predetermined first reference amount; - a second detection processing unit that is configured to detect a second state, the second state being a state where the remaining amount of the developer housed in the developer housing portion (316, 326, 336, 346) mounted to the mounting portion (317, 327, 337, 347) is equal to or more than the first reference amount and less than a predetermined second reference amount, the second reference amount being larger than the first reference amount; - a first release processing unit that is configured to release the regulation on the attachment/removal of the developer housing portion (316, 326, 336, 346) by the lock mechanism (318, 328, 338, 348) when the first detection processing unit detects the first state; - a second release processing unit that is configured to release the regulation on the attachment/removal of the developer housing portion (316, 326, 336, 346) by the lock mechanism (318, 328, 338, 348) when the second detection processing unit detects the second state and a predetermined release condition is met; and characterized by - a display processing unit (54A, 54B) that causes a display to display a release operation screen when the second detection processing unit detects the second state while a door opening of a cover member is detected, the cover member being opened and closed to attach and remove the developer housing portion (316, 326, 336, 346), the release operation screen being used for a release operation of the regulation on the attachment/removal of the developer housing portion (316, 326, 336, 346) by the lock mechanism (318, 328, 338, 348),