An ink jet printer module has a module body, an ink inlet port, a washing liquid inlet port and a pneumatic inlet port connected with the main ink tank, the washing liquid tank and the pneumatic pump. A common flow path in the interior of the module body selectively communicates with either the washing liquid flow path or the washing liquid flow path. An ink opening and closing valve is provided at the module body. A pneumatic and washing liquid selection valve is provided in the module body An ink discharge port is provided in the module body discharges the ink of the ink flow path to the outside of the module body. A common discharge port is provided in the module body and discharges either the pneumatic or the washing liquid of the common flow path.