An eraser includes a housing (20) having a receiving chamber (21), a collection zone (23) and a plurality of reinforcing ribs (26), a mounting board (30) mounted on the housing, a cleaning member (40) mounted on the mounting board, a support bracket (50) mounted on the housing, a door (60) removably mounted on the housing to cover the collection zone, a hollow separation member (70) mounted in the housing to separate the receiving chamber from the collection zone, and a control valve (80) movable to open the separation member so as to connect the receiving chamber with the collection zone or to close the separation member so as to interrupt a connection between the receiving chamber and the collection zone, and two decorative covers mounted on the housing and each abutting the reinforcing ribs.