A connecting device configured to connect two construction materials arranged at a distance therebetween, that is, a door frame, a base member, and a reinforcing member of a wall includes a connecting member including a locking portion capable of being locked with a locking target member arranged at one construction material along a thickness direction perpendicular to a direction of the distance and a coupling portion configured to be moved in the thickness direction and coupled to the other construction material by a drill screw as a coupling fitting are arranged at an end on a side of the one construction material and an end on a side of the other construction material. When the coupling portion is not coupled to the other construction material, the locking portion is movable in the thickness direction with respect to the locking target member.