Abstract: A water shut-off device for a water purifier that assures automatic blocking of water flow at the time of changing of a used filter comprises a connector having a water inlet passageway and a first connector port in communication with the inlet passageway, the first connector port provided with a valve chamber. A valve body is movably fitted into the valve chamber for selectively closing and opening the first connector port. Removably coupled to the connector is a filter which has an inlet port connectable to the first connector port of the connector, a filter element, an outlet port and a pusher for, when the inlet port is brought into connection with the first connector port, causing the valve body to move into a position wherein the first connector port is opened to allow water flow.