The multi-wire saw is used for processing of silicon wafers for solar cells or IC. This slicing method uses the working fluid mixed abrasive grains called slurry. Therefore, the compositions or the supply states of slurry affect the processing characteristics of the multi-wire saw. In the work descent type of multi-wire saw, it is difficult to supply the slurry directly to the processing area, and the slurry actions affect the processing characteristics. This study treated the supplying methods to prevent air into the slicing groves. In addition, the slurry actions in slicing grooves were observed using a high-speed video camera. This study examined two supply methods involving dipping and using a supply assistant board.