The parameter dependence of antenna loading resistance for ICRF waves using a T-shaped rotatable antenna is investigated in the TNT-A tokamak. When the antenna current is parallel to the toroidal field, the loading resistance increases with the mean plasma density, but depends weakly on the toroidal field, the ratio of hydrogen to deuterium concentrations and the type of the Faraday shield. Similar results with a lower value of the loading resistance are obtained in the case where the antenna current is perpendicular to the toroidal field, using the same rotatable antenna. With the antenna current parallel to the toroidal field, the loading resistance for a low parallel refractive index nz is larger than that for high nz.