In MIMO transmission, efficient communication is provided by beneficial use of radiation pattern and polarization. In this paper, we use a dual-polarized directional MIMO antenna as an indoor base station, and examine about the transmitting antenna selection from four elements to two elements based on measurement data. We show that minimum BER is obtained by the selection maximizing minimum eigenvalue (2nd eigenvalue). We reveal that maximum channel capacity is achieved at the receiving positions of 72.7% by this selection method, and the improvement factor is 20.8% compared with the expectation of the random antenna selection.