The basic magnetic properties are reported for Eocene andesite and granitic andesite collected from the King Sejong Station and Marsh Runway at King George Island, South Shetland Islands Antarctic Peninsula. Samples A (andesite), B (granitic andesite) and D (granitic andesite) carry stable component of natural remanent magnetization (NRM), but sample C (andesite) unstable URM. These NRM stabilities are consistent with the domain structures estimated by the ratios of $J_R/J_s;and;H_{RC}/H_C$ values. On the basis of their Curie temperature, we infer magnetite as the main magnetic carrier for samples A B and C and titanomagnetite for sample D. Our study reveals that samples A and B are suitable for paleomagnetic investigations, whereas sample D is not.