An ink supply device is provided in correspondence with a recording head unit.
The recording head unit has a recording head that ejects ink drops onto a recording
medium on the basis of image information. Additionally the recording head unit
has a sub ink tank provided with an air communication hole. The ink supply device
includes an ink supply unit that supplies ink to the sub ink tank by reducing pressure
on the inside of the sub ink tank through a pressure reduction part. A sealing
part at least implements sealing of the air communication hole while the ink supply
unit is reducing the pressure inside the sub ink tank.
