To solve the problem that a plurality of devices having different versions come to exist if processing is interrupted in the middle of updating when the plurality of devices are updated to a software of the same version so that users can use the software.

A software update device is a device for updating a software of a device connected to a network, and has means for determining whether to be software compulsory distribution, means for determining whether a software distribution time is a distributable time zone, means for rescheduling software update if not the distributable time zone, means for distributing a software to a distribution object device, means for determining whether the current time is included in an applicable time zone, means for calculating an application end schedule time, means for determining whether software application can be performed within an updateable time, and means for applying the software.