A semiconductor device in which consumption of power attendant on a leakage current
in a block where the power is turned on and off intermittently is reduced. In the
semiconductor device according to the present invention, an error check necessity
judgment circuit judges on notification from an error check necessity notification
circuit located in a block where the power is not disconnected whether an error
check must be made, and an error check execution circuit makes an error check on
data loaded from an external memory at the time of a boot in accordance with the
judgment of the error check necessity judgment circuit. An error check cannot completely
be omitted. Therefore, to ensure the reliability of a system, an error check is
forcedly made once whenever a boot is performed times set by an error check interval
setting circuit. This shortens intermittent operation time by time taken to make
an error check, resulting in a reduction in consumption of power attendant on a
useless leakage current.