We utilized autoradiography to visualize radioactive contamination in the skeletal muscles of a pig raised within 20 km of the Fukushima Daiichi nuclear power plant following the nuclear accident. The autoradiogram of control muscle showed relatively homogenous exposure. In contrast, the autoradiogram of affected muscle showed a heterogeneous and sporadically dense imaging pattern. Photo luminescence densities of the affected and control muscles were 3.89 ± 0.67 and 2.13 ± 0.43 PSL/mm2, respectively. This difference indicated that radioactive cesium was distributed in the skeletal muscle of the affected pig.