To provide an undergroundwater passage type pneumatic caisson, which does not obstruct the passage of undergroundwater more than required.

In the pneumatic caisson 11 with an approximately cylindrical caisson skeleton 12, a work-room slab 13 installed on the lower side of the skeleton 12 and a caisson cutting edge 14 mounted on the lower side of the slab 13, water-passing layers 18, 19 and 20, through which undergroundwater can be passed, are secured to at least one of the skeleton 12, the slab 13 and the cutting edge 14.