A drug in the form of a solid preparation soluble or suspendable in water or an aqueous solution characterized by containing at least one biocompatible, gastric motility suppressing component such as triacetin, which is capable of transmitting ultrasonic wave to a target organ via the solution pooled in the body in a noninvasive examination (for example, an ultrasonic examination of an abdominal organ), identifying the area in which the solution exists, or clarifying the boundary of the solution and an organ in contact therewith, is employed as an auxiliary agent in the examination. In addition, triacetin can be extensively used as a gastric motility suppressor.