A image reading device comprises a reading part for reading a document, a storage part including shared space, and an operation part for accepting input of identification information when the device is in a logged-out state, entering a logged-in state when a user is successfully certified, accepting settings input and function execution input when the logged-in state is in effect, and entering the logged-out state when predetermined conditions are met, the operation part including a scanning START key for accepting instructions to perform scanning using the reading part. When the scanning START key is pressed while the device is in the logged-out state, the reading part reads a document and forms image data, and the storage part stores the image data formed by logged-out scanning in the shared space.