To prevent cervical damage by constraining the movement of the neck of a pilot seated on a seat main body, and fixing the upper half body to the seat main body before election.

This ejection seat device is provided with an expandable constraining member 13 arranged around the neck to constrain the movement of the neck of a pilot 5 before the ejection of a seat main body 4, a gas generator 14 fitted to the seat main body 4, and a control valve 15. Multiple shrunk air bags are fitted to a helmet 10 along the periphery of the neck as the constraining member 13, and the movement of the neck of the pilot 5 is constrained when the air bags are expanded. A pair of the right and left belts 21 wrappable on the right and left shoulders of the pilot 5, a pair of the right and left winding bodies built in the seat main body 4, and a rotary drive motor are provided to fix the upper half body of the pilot 5 to the seat main body 4. The belts 21 are connected to the winding bodies at one end and releasably connected to the seat main body 4 at the other end. The attitude of the pilot 5 can be surely and properly controlled in a short time immediately before ejection.