To produce several types of natural plant sponge cucumber sheets by slicing up a piece of natural plant dried sponge cucumber, and to employ a natural plant dried sponge cucumber sheet into a luminaire, a partition or the like after a natural plant sponge cucumber sheet is coated with synthetic resin.

This manufacturing method includes the following three processes. In a first process (a), by cutting through the side of a natural plant dried sponge cucumber in a longitudinal direction, its center core is removed. In a second process (b), water is absorbed into the natural plant dried sponge cucumber, and then this natural plant sponge cucumber 20 is sent to a slicing machine 22 so that a rotary blade 30 can slice it up in a shape of sheet. In a final process (c), a sliced natural plant sponge cucumber sheet is coated with synthetic resin. In some cases, a dyeing process is provided between two processes (b) and (c) mentioned above.