A separation device includes a separator that separates a recording medium from a rotator and a plurality of recesses disposed on a conveyance path side face of the separator over which the recording medium is conveyed in a recess span in a recording medium conveyance direction and at least in a conveyance span where the recording medium is conveyed. The plurality of recesses includes a first recess extending in a first extension line that is oblique relative to the recording medium conveyance direction and a second recess being adjacent to the first recess in a direction perpendicular to the recording medium conveyance direction. The second recess extends in a second extension line that is oblique relative to the recording medium conveyance direction and overlaps the first extension line of the first recess in the direction perpendicular to the recording medium conveyance direction to define an overlap span.