In a recording medium output apparatus that is assembled to an image forming apparatus and outputs a sheet-like recording medium being transported onto a stack tray on which recording media are stacked, the recording medium output apparatus includes an output unit and a drive unit. The output unit is free to move in a recording medium width direction intersecting the transport direction of the recording medium being transported and outputs the recording medium toward the stack tray at a position higher than that of the stack tray, and the drive unit moves the output unit in the recording medium width direction before and after the trail edge of the recording medium to be output from the output unit leaves the output unit.