An image erasing method, according to an embodiment, includes the steps of supplying a sheet from a sheet supply section and conveying the sheet from the sheet supply section on a first conveying path. The method further includes controlling, based on a selected mode, the first conveying path, a reader, a second conveying path, an erasing unit, and a switching section. When the selected mode is an erasing mode, the sheet is conveyed on the first conveying path without being read by the reader, conveyed on the second conveying path where the image is erased by the erasing unit, and then conveyed to a discharge tray. When the selected mode is a reading mode, the sheet is conveyed on the first conveying path where the surface of the sheet is read by the reader, and then conveyed to the discharge tray without being conveyed on the second conveying path.