Abstract: A terminal connecting device includes a main body of a terminal block having diaphragms and supporting strips, a terminal plate positioned at the top of the supporting strips, movable terminals supported by a spring to attach or detach lead wire positioned on the terminal plate, a restraining structure, proximate to the movable terminals, which limits the movement of the lead wire, and a terminal screw coupled with the movable terminals after being penetrated through the through hole of the lead wire and fastened at a screw hole of the terminal plate. The restraining structure restricts the lead wire from diverting or dropping, thereby preventing safety accidents such as stopping the operation of facility or electric shock. The restraining structure also allows easy penetration of the terminal screw through the through hole of the lead wire in fixing the lead wire, thereby improving productivity due to ease of fastening the terminal screw.