Toluene and xylene are widely used as industrial solvents. Concentrations of toluene and xylene in the air were measured as time lapsis at the paint shop in the shipbuilding company using thinner. Air density of toluene and xylene were relative low in the place where the room has extremely high ceiling or opened. In contrast to this, the density were high in the room in which the ceiling was low. In the room where ceiling is opened, concentration of toluene and xylene markedly decreased after painting work, but in the case that the room is closed in which concentration is very slow.