An image reading device includes a reading unit having a light-receiving unit and a light-emitting unit emitting a plurality of lights of different colors toward a reading position. An opposing member is disposed opposite the reading unit with the reading position interposed therebetween. The controller controls the light-emitting unit to emit the lights and the light-receiving unit to receive the lights thereby acquiring an intensity of each light. The controller determines that a sheet is not present when relationships among intensities of the plurality of lights are same as the first intensity relationships. The first intensity relationships are defined by intensities of the plurality of lights reflected by the opposing member and received by the light-receiving unit. The first intensity relationships are different from intensity relationships of the plurality of lights reflected by a sheet present at the reading position and received by the light-receiving unit.