A power supply switching device comprising: a first switching unit (33, 36, 37) for disconnecting a power storage and a load from a power system and interconnecting the power storage and the load with the power system; a second switching unit which is disposed at the primary side of the first switching unit (33, 36, 37) and for disconnecting the power storage and the load from the power system and interconnecting the power storage and the load with the power system; a first voltage detector which is disposed at a primary side of the first switching unit (33, 36, 37) and at a primary side of the second switching unit, and which is adapted to detect a voltage of the power system; and a second voltage detector which is disposed between the first switching unit (33, 36, 37) and the second switching unit, and which is adapted to detect a voltage of the power system; and a controller which is configured to actuate the first switching unit (33, 36, 37) and the second switching unit to disconnect the power storage and the load from the power system upon absence of a detection of the voltage of the power system by the first voltage detector, when the first switching unit (33, 36, 37) is disconnecting the power storage and the load from the power system and the first voltage detector detects the voltage, and then a user operates the second switching unit to interconnect the power storage and the load with the power system and the second voltage detector detects the voltage of the power system, determine that the user has given an instruction and actuate the first switching unit (33, 36, 37) to interconnect the power storage and the load with the power system. a first switching unit (33, 36, 37) for disconnecting a power storage and a load from a power system and interconnecting the power storage and the load with the power system; a second switching unit which is disposed at the primary side of the first switching unit (33, 36, 37) and for disconnecting the power storage and the load from the power system and interconnecting the power storage and the load with the power system; a first voltage detector which is disposed at a primary side of the first switching unit (33, 36, 37) and at a primary side of the second switching unit, and which is adapted to detect a voltage of the power system; and a second voltage detector which is disposed between the first switching unit (33, 36, 37) and the second switching unit, and which is adapted to detect a voltage of the power system; and a controller which is configured to actuate the first switching unit (33, 36, 37) and the second switching unit to disconnect the power storage and the load from the power system upon absence of a detection of the voltage of the power system by the first voltage detector, when the first switching unit (33, 36, 37) is disconnecting the power storage and the load from the power system and the first voltage detector detects the voltage, and then a user operates the second switching unit to interconnect the power storage and the load with the power system and the second voltage detector detects the voltage of the power system, determine that the user has given an instruction and actuate the first switching unit (33, 36, 37) to interconnect the power storage and the load with the power system.