An apparatus for testing object strength includes a support platform, a force gauge for reading push or pull force exerted on an object, an installation mechanism for slidable installation of the force gauge on the support platform, an installation board supporting the object, a pull-push mechanism connected to the force gauge to be pushed or pulled by the force gauge and exert force on the object, and an adjustment mechanism. The adjustment mechanism includes a pedestal secured to the support platform, a slider slidably mounted to the pedestal, an adjustment rod pivotally mounted to the pedestal and threaded into the slider, and a manipulation member fixed to the adjustment rod. The manipulation member rotates the adjustment rod relative to the slider. Thus the slider slides relative to the pedestal. The installation board adjusts the object relative to the support platform.