A development system includes a development roller that carries developer, a developer supplying roller that supplies developer to the development roller, a developer container that supplies developer to the developer supplying roller, and a photoconductor on which a developed image is formed with the developer carried by the development roller. The developed image is transferred on the photoconductor. A toner tank reserves developer having a higher concentration than that of the developer in the developer container. A liquid carrier tank reserves liquid carrier. High-concentration developer is fed from the toner tank and liquid carrier is fed from the liquid carrier tank into a developer concentration adjusting tank. A developer concentration adjustment controlling section controls development conditions depending on an input paper type.