Toner replenishment units include an upper toner container, a lower toner container, a first vertical conveyance pipe, a second vertical conveyance pipe, a third vertical conveyance pipe, a first horizontal conveyance pipe, a second horizontal conveyance pipe, and a confluence section. A first conveyance screw is included in the horizontal conveyance pipe and a second conveyance screw is included in the second horizontal conveyance pipe. A first inter-axis distance between a first horizontal rotation axis of the first conveyance screw and a third vertical pipe axis of the third vertical conveyance pipe, and a second inter-axis distance between a second horizontal rotation axis of the second conveyance screw and the third vertical pipe axis are set to take a different value.