In an image reading device, a storing device stores reference dark output data and reference correction data. A control device, after a command receiving unit receives an instruction to read an original document, generates dark output data based on read data while the light source does not emit light. The control device determines whether the dark output data is within a first prescribed range into which the reference dark output data falls. The control device selects the reference correction data as selected correction data, when determining that the dark output data is within the first prescribed range. The control device generate correction data to correct the image data when determining that the dark output data is not within the first prescribed range, and selects the generated correction data as the selected correction data. The control device corrects the image data by using the selected correction data.