A toner replenishment device has: a toner reservoir section for supplying a toner to a development device; a supply fluid conveyance section for conveying a fluid mixture of toner and air from the toner reservoir section through a supply conveying path; a toner separation section for separating the fluid mixture which has been conveyed by the supply fluid conveyance section into the toner and the air and supplying the toner to the development device; a circulation fluid conveyance section for circulating at least air separated from the fluid mixture, from the toner separation section to the toner reservoir section through a circulation conveyance path; and a capacity variable member connected with the supply conveying path or the circulation conveyance path, capable of absorbing a pressure fluctuation of the fluid mixture or the air by varying a capacity of the member.