A punching bag is provided. The punching bag is positioned on a fixed pillar, and comprises a supporting frame, a foam layer, a force-bearing plate, and a punch pad. The supporting frame is attached and fastened to the fixed pillar. The foam layer is disposed on the supporting frame, and at least a sensing element is positioned on a surface of the foam layer for measuring an external punch force. The force-bearing plate is disposed on the foam layer and utilized for covering the foam layer, wherein at least an elastic element correspondingly attached to the at least a sensing element is positioned on an inner side of the force-bearing plate. The punch pad is utilized for covering and attaching to the force-bearing plate to bear the external punch force.