A development agent supply device includes a casing having an opening, a first development agent storage section, and a second development agent storage section, a development agent holding member housed in the casing such that a development agent holding surface thereof faces a developer-supplied device via the opening, a first electric-field transfer board that transfers development agent with a traveling-wave electric field along a down-facing development agent transfer surface in a predetermined direction from the first development agent storage section to the opening and faces the development agent holding surface at a downstream end in the predetermined direction, and a development agent retrieving unit that agitates development agent stored in the second development agent storage section and inadequately-charged development agent falling from the development agent transfer surface and conveys the development agent to the first development agent storage section.