To provide a fixing device for a partition panel with which mounting/dismounting work is performed in a short time without losing a tool.

The fixing device fixes the partition panel to the top board, wherein the partition panel has a notched portion having a substantially U-shape in a side view and provided at one side end of the lower part of the partition panel, and holds a side edge of a longitudinal side of the top board therein to be mounted to the top board. The fixing device includes: a fixing device body formed with a region fixed to the lower side part of the notched portion of the panel, the lower side part positioned on the lower surface side of the top board, the region having a top board fixing portion including a fixed side having a substantially T-shape in the front view and a lower side fixing portion for a panel; a top board tightening/loosening member for fixing the fixing device body to the top board through the top board fixing portion; a lower side part tightening/loosening member for fixing the fixing device body to the partition panel through the lower side fixing portion; and a tool holding portion for removably holding the tool for fastening/loosening at least one of tightening/loosening members.