The present study is concerned with experiments and analyses of the movement of a liquid drop in a horizontal circular pipe exposed to air flow unjected from a vertical circular pipe. Each inner diameter of the pipes is 30mm and both ends of the horizontal pipe are open to the atmosphere. In the first experiment, a water drop is softly put on the inner wall of a horizontal acrylic resin pipe and its shape is examined. The approximate drop shape can be calculated from the law of minimum energy and the information obtained about the contact angle. In the second experiment, a water drop is exposed airflow on a curved wall. It is clarified that this phenomenon is closely related to the gas flow in the horizontal pipe. And the relation between air flow and the stop position and the split-phenomena of liquid drop are examined experimentally and analytically.