A power system with an electric rotating machine providing an operation of power generation and power running, a switching circuit providing electricity for each phase, by switching a plurality switching elements ON/OFF by the electric rotating machine, a battery section connected to the switching circuit, and switches on electrical pathway, between the switching circuit and the battery section. A power shutoff section to shutoff an electrical pathway when an overcurrent flows in, at least one of the electric rotating machine and the switching circuit. Power control devices are provided with an overcurrent determination which determines that an overcurrent has occurred, based on results of, a first determination that determines a current flow has increased to a predetermined over current threshold, and a second determination that determines that current flow has decreased thereafter, and a switch control that switches the switches open based on a determined result of the overcurrent determination.