An aircraft fuselage assembling jig includes: a base provided with a plurality of frame indexes for positioning both ends of a plurality of aircraft fuselage frames; a plurality of header plates, each of which protrudes from the base so as to extend along an aircraft fuselage panel, the header plates being arranged parallel to each other in an axial direction of the aircraft fuselage panel; and a plurality of electric cylinders radially provided on each of the plurality of header plates, the electric cylinders moving respective receiving members in a radial direction of the aircraft fuselage panel, the receiving members contacting a skin included in the aircraft fuselage panel.