The compaction of powder has been simulated on two-dimensional numerical model by employing a digital computer. In the process of formation of the initial bed, 400 discs of equal size were dropped one by one into a container, introducing the probabillity P to make each two discs cohere in contact.
The successive packing of beds by subjecting them to vibratory or tapping treatment has also been simulated by using the above mentioned bed generated. Each disc is shifted in turn to the hole which existed in the lower layer. In this process the cohesion probability P' was taken into consideration.
For the data of porosity and tapping number we followed Kawakita's and Kuno's empirical equations, and it was indicated that the cohesion probability P' is closely related to the rate constant in those equations.