An inkjet printer includes a body housing a print engine. The water filter device includes a filter unit to purify the water supplied from the water supply source, a storage tank unit to store the water purified through the filter unit, a case to accommodate the filter unit and the storage tank unit, a filter head assembly, and a water filter assembly separably coupled to the filter head assembly. When the pressure difference between the main conduits becomes small, the pressure selector valve is automatically returned to a neutral position to cut off communication between the main conduits, suppressing a reversing movement of the hydraulic motor so that an inertial body can be brought to a stop smoothly.