A head unit of an ink jet printer is formed with a mist removing space for removing an ink mist generated when an UV ink is discharged by an ink jet head from a gap between the head unit and a table, where the mist removing space is formed with a gas introducing port, arranged at a position between the ink jet head and the LED, for the gas to be introduced from the gap side between the head unit and the table to the mist removing space, an intake port for the gas to be suctioned from the mist removing space toward a sirocco fan side by an airflow generated by the sirocco fan, and a gas discharging port, arranged separately from the intake port, for the gas to be discharged from the mist removing space.