To provide a nut positioning jig capable of shortening the operation time of a position adjusting operation of a nut upon the fitting of a ceiling-embedded air conditioner, and to provide a fitting method of the ceiling-embedded air conditioner using the nut positioning jig.

A nut positioning jig 30 includes: a fitting part 31 fitted to a hanger bolt 20; a nut position display part 32 which is arranged along the shaft center direction of the hanger bolt 20 in such a state as to be fitted to the hanger bolt 20 and allows a display mark 36 for exhibiting a fitting position of a lower nut located on the lower side of an upper nut and the lower nut to be attached thereto; and a contacting part 33 which is formed so as to be extended in the right angle direction with respect to the longitudinal direction CY of the nut position display part 32 on the lower side of the nut position display part 32 and be brought into contact with the lower surface 111 of the ceiling material 110.