With a state in which electric power is not supplied to respective
functional units as a basis, an information processing apparatus is
capable of performing power control to supply electric power to the
respective functional units to cause the functional units to perform
processing only when the functional units are required to be operated
and, after the end of the processing, stop the supply of electric power.
Therefore, in particular, it is also possible to set the state in which
electric power is not supplied as a basis for a CPU, a leak current of
which causes a problem. This is more advantageous in terms of a circuit
size and easiness of control than applying power control to the
respective functional units. Moreover, since the state in which electric
power is not supplied is set as a basis, processing for shift of a state
is reduced and, when operation is performed, it is possible to speed up a
response to the operation compared with the time when a suspend mode or
the like is used.