It is surely of importance to estimate the numbers of living bacilli in a suspension of tubercle bacilli. Neverthless, the accurate calculation method of living tubercle bacilli has not been developed, since there are much difficulties in culculating tubercle bacilli by pour-plate method, which is employed widely for culculation of the numbers of ordinary living bacilli. As is known, it is very difficult to let tubercle bacilli grow in the depth of solid media, and evaporation of solid medium poured in Petri dish is inevitable for a long period cultivation of tubercle bacilli.The purpose of the present report is to dissolve the difficulties above mentioned, by using the Kirchner agar medium containing some growth promoting substances for tubercle bacilli, and by employing scotch cellulose tape for prevention of drying up of the solid media.