Abstract: A duplicate notepaper case consists of a main case body, a subordinate case body, a perpetual calendar socket and a moveable pen inserting socket, whereas the main case body is a sandwich space formed by an upper cover and a bottom socket, its hollow interior is a concave to accommodate notepaper, the pen socket mounted in the central back portion of the main case body has an arm at its side which has a shaft pin pivoted in the corresponding shaft hole in the main case body so that the pen socket can swing to one side of the main case body by means of the shaft pin.