A storage device is disclosed. The storage device includes a text/image information memory unit, a unit that converts the data format of text/image information, a unit that communicates with a user terminal having a display, and a delivery unit configured to, in response to a request for the property of a file stored in the memory unit from the user terminal through the communication unit, show the property of the corresponding file stored in the memory unit on the display of the user terminal. When the user terminal requests a download of the file by selecting a file format applicable to binary image data, the conversion unit converts text/image information contained in the file into binary image data if the data format of the text/image information is not binary image data but is multilevel image data (color image). Then, the delivery unit sends the binary image data in the selected file format to the user terminal.