To provide an underground gas detection device which detects underground gas by a simple constitution irrespective of the kinds of gases.
The underground gas detection device includes a packer 2 for shutting off the flow of underground water and gas in the axial direction of a hole in the hole 7 drilled in base rock G, a strainer pipe 3 for connecting the packers 2, 2 along a hole wall, pressure sensors 41 etc. which are arranged in the strainer pipe and measure the pressure at a plurality of places in the axial direction of the hole, and a water feeding pipe 5 for remotely expanding the packers. The pressure sensors 41 are configured to be formed at a plurality of places at intervals in the axial direction of the hole at one continuous optical fiber 4.
IMAI HIROSHI
KAWAKAMI JUN
