As the bulk density of biomass material is low, some problems are encountered during storage, transport and usage of biomass. In order to overcome these problems, densification process is necessary to increase the bulk density of the biomass. Biomass characteristics are improved, the volumetric heating value of biomass is increased, transportation and storage costs of biomass are reduced and the combustion characteristics of biomass are improved by a biomass densification process. Nowadays, pelletizing machines are widely used in the course of biomass densification. During the pelletizing machine's operation, obtaining the high quality compressed biomass with high capacity and less energy consumption is closely related to the pelletizing machine’s design criteria. Therefore, it is necessary to investigate all parameters that affect the pelletizing machine performance. In a laboratory scale, biomass pelletizing and densification tests are carried out by means of simplified pelletizing apparatus. Unfortunately, the tests that are executed by means of these apparatus, because of their operation principle, can not completely illustrate the pelletizing process and the forces which occur during this process. As the current systems which are used to simulate the pelletizing process are not sufficient, in order to clarify, model and optimize the pelletizing process much more effectively and to obtain necessary reliable data for pelletizing machine design, development of a new apparatus is necessary. The requirement of developing a new biomass pelletizing test device and its design principles are explained in this study.