To provide a simple mounting structure of a riser which enables installation of the riser with excellent work performance along as well as easy replacement of the riser.

The structure of mounting a riser A at a lower part of furniture between its left and right side boards through a fixing member 1 and the fixing member 1 comprises imbedding parts 11 fitted into bottomed hole parts 2 bored in the rear of the riser A at its left and right side end parts and pointed protruding parts 12 provided respectively onto the imbedding parts 11. The pointed protruding parts 12 are driven into the edges 31 of the left and right side boards to mount the riser A. Preferably, anti-slipping-out ribs 111 are raised on the outer peripheral surfaces of the respective imbedding parts 11.