A radio communication device according to the present invention adaptively
controls directivity of a transmission radio signal by using a plurality
of element antennas on the basis of a received radio signal received from
a communication target counterpart radio communication device. The radio
communication device includes a transmission controller configured to
process the transmission radio signal according to a first control method
for adaptively controlling the directivity, a propagation path state
detector configured to detect fluctuation state of a propagation path to
a counterpart radio communication device, and a judgment unit configured
to judge whether or not to change the directivity on the basis of the
fluctuation state of the propagation path. If it is judged that the
directivity is to be changed, the transmission controller switches to a
second control method that is different from the first control method,
and processes the transmission radio signal according to the second
control method.