An apparatus for removing reflected light is provided, which is used for a measuring device that emits a sheet-like beam of light onto suspended particles and measures light scattered from the suspended particles. The apparatus includes a light introduction unit, a light reflective unit, a light sealing unit and a light absorption member. The light introduction unit has a first aperture, a second aperture, and a passage through which the light travels from the first aperture to the second aperture. The light reflective unit disposed opposite to the second aperture allows the light having traveled through the second aperture to reflect toward a predetermined direction so as to prevent the light from returning into the second aperture. The light sealing unit in which the light reflective unit is disposed has an inner wall to confine the light reflected from the light reflective unit.