A toggle-type die-fastening apparatus has a movable platen that carries one mold part and is supported by and guided along a plurality of tie bars whose one ends are fixed to a fixed platen on which another mold part is mounted. The other ends of the tie bars are supported by a toggle support, and a toggle mechanism is disposed between the toggle support and the movable platen for pressing the mold part carried by the movable platen against the mold part mounted on the fixed platen. A die-fastening force adjusting nut is threaded onto the end portion of each tie bar that is closer to the toggle support so as to bear the reaction of the die-fastening force generated by the toggle mechanism. An adjusting cylinder is formed in this portion, and it is connected to a hydraulic circuit so that the pressure within each of the cylinders is controlled by a pressure adjusting valve in such a manner as to correspond to a die-fastening force set by a setting device. Therefore, the die-fastening forces of all the tie bars can be made the same, thereby eliminating any imbalance between the die-fastening forces of the tie bars caused by changes in thermal balance during the operation of the molding machine.