To exchange power units where abnormality occurs without cutting the power source of a system when abnormality occurs in the power unit by detaching the power unit where abnormality occurs from a commercial power source and loads.

The loads L1-L4 in an information processor 10 are connected to load switching devices LS1-LS4 and the load switching devices LS1-LS4 are connected to the prescribed power units among the power units P1-1 to P4-2. The power units P1-1 to P4-2 are connected to an abnormality detection device 21 provided in a power controller 20, and the power controller 20 is connected to the load switching devices LS1-LS4 and the power switching devices PS1-PS4. When abnormality occurs in any power unit, the abnormality detection device 21 informs the power controller 20 of it. Thus, the power unit where abnormality occurs can be detached from the commercial power source 30 and the loads.