The present invention provides a power control device for controlling the transmission
power of a signal transmitted between a mobile station and a base station in a
mobile communication system via a radio channel. The device has an error judgment
unit for receiving communication data transmitted in each communication unit having
a fixed length via the radio channel, and judging whether or not said communication
data has an error in each communication unit; and a target power control unit for
measuring in each predetermined measurement period the number N of said received
communication units and the number M of communication units which are judged as
error by said error judgment unit, and changing said target power value based on
a criterion value and said number M, or said criterion value and said numbers N
and M, said criterion value being a criterion of change of said target power value
and being determined according to said number N.
