An image forming apparatus includes a storage case, a developer conveyance portion, a developer detecting portion, a time measuring portion, and a driving control portion. The storage case stores developer that is supplied to a developing device, and conveys the developer by driving a first conveyance member. The developer conveyance portion conveys, by driving a second conveyance member, the developer supplied from the storage case. The developer detecting portion is provided in the developing device and detects the developer supplied from the developer conveyance portion. The time measuring portion measures a required time between a time when the first conveyance member starts to be driven and a time when the developer detecting portion detects the developer. The driving control portion sets a driving time of the second conveyance member based on the required time measured by the time measuring portion.