A liquid droplet ejecting apparatus comprises an ejecting head including a passage which is connected to a sub-tank and an ejecting pressure applying device which applies a feed pressure to the liquid inside the passage, a main tank detector which detects that a main tank is mounted to a main tank mounting portion, a suction pump which applies a negative pressure to an air layer inside the sub-tank to discharge air from inside the sub-tank to outside, and a controller configured to control the suction pump and the ejecting pressure applying device, based on information from the main tank detector. The controller causes the suction pump to discharge the air from inside the sub-tank to outside and causes the ejecting pressure applying device to eject the liquid from a nozzle, when the main tank detector detects that the main tank is mounted to the main tank mounting portion.