A fluid ejection device includes a fluid ejection tube having a forward end nozzle inserted into an abdominal cavity. The fluid ejection tube, accommodated in a cylindrical casing section, is movable in an extending direction. The fluid ejection tube moves in the extending direction, interlocked with a sliding operation of a sealing state switching operation section on the outside of the casing section. Fixed and sliding sealing sections, which seal the inside of the abdominal cavity off from outside, are arranged between the fluid ejection tube and an inner wall surface of the casing section. The fixed and sliding sealing sections shift from a first sealing state with a first airtightness to a second sealing state with a higher airtightness, through movement of the fluid ejection tube by the sealing state switching operation section. The fluid ejection device is electrically drivable when the second sealing state is established.
