A testing instrument (10) is configured by coupling a pipe (12), a cover (13), a filter member (14), and a detector (15). These members each have a hollow shape, and a series of pipe portion is configured by coupling them to each other. The pipe (12) has a plurality of holes penetrating the pipe (12) from the outer surface to the inner surface. The cover (13) covers these holes and guides a reagent to the holes from an inflow port. An inhalation tool (11) to be held in the mouth of a subject is installed on the pipe (12) in a detachable manner. A reagent gas mixture is supplied to the cover (13) from a reagent supply unit (20). Inhalation of the reagent induces the subject to cough, and airflow generated by the cough flows through the pipe portion. The detector (15) detects strength of the airflow flowing through the pipe portion and outputs a detection signal to a measuring unit (30).
