A power system capable of detecting a foreign object, includes a power supplier side, a power receiver side, and a cable. The power supplier side includes a power converter, a foreign object detection and control circuit, and a pull-up circuit. The power converter supplies a supply voltage to the power receiver side according to a power supply control signal. The foreign object detection and control circuit generates the power supply control signal for controlling the power converter, and generates a foreign object detection and control signal according to a voltage at a supplier transmission node of the power supplier side, for determining whether a foreign object exists in the power receiver side. The pull-up circuit adjusts a level of a supply current which is supplied from the supplier transmission node to the power receiver side.