A sheet conveyer device is provided. The sheet conveyer device includes a sheet tray, a feeder roller, a separator roller, a roller holder to rotatably support the feeder roller and to be coupled with the separator roller, spreading from a separator roller side toward a feeder roller side, to be movable between a first position and a second position, a manipulation arm configured to be coupled to the roller holder and to manipulate the roller holder to move between the first position and the second position, and a driving unit to drive the manipulation arm to move the roller holder. The manipulation arm is coupled to the roller holder at a coupled section, which is in a position between the feeder roller and the separator roller and in a position between two tangent planes which are common to the feed roller and the separator roller.