To provide an uninterruptible power device capable of continuing the operation even when some cooling fans fail and stop.SOLUTION: The uninterruptible power device is configured so as to, when a first variable cooling fan of multiple variable cooling fans stops and when a temperature sensor detects that the temperature inside the device has exceeded an abnormality detection level, control the rotation speed of a second variable cooling fan which is operating normally other than the first variable cooling fan so that the temperature inside the device is kept below the abnormality detection level.SELECTED DRAWING: Figure 2