PURPOSE: To prevent capping during molding by forming through-holes between the surface of a mortar hole and the outside surface of a mortar.

CONSTITUTION: The horizontal hole 4 is provided on one side in the upper part of the mortar 2 and the vertical hole 5 is formed so as to connect to the hole 4. The surface of the mortar hole 1 and the outside surface of the mortar 2 are penetrated through the holes 4, 5. Air can be vented not only from the horizontal hole 4 but from the vertical hole 5 as well at the time of compressively molding granular particles 7 by using an upper pestle 6 and a lower pestle 8. The capping by which the surfaces of tablets are exfoliated is thus thoroughly prevented even in the case of molding the granular particles 7 having high voids.