The utility model relates to an underground leakage observation instrument, relating to a leakage observation instrument and solving the problem of low observation accuracy of the existing leakage observation method. The bottom of a concave-bottom leaking water collector is provided with a water outlet and an air inlet, the air inlet of the concave-bottom leaking water collector is communicated with an air outlet of an air intake pipe, and the water outlet of the concave-bottom leaking water collector is communicated with a water inlet of a water pumping pipe; the opening of a leaking water extraction bottle is sealed by a sealing device, the sealing device is provided with a water inlet and an air outlet, and the water outlet of the water pumping pipe is communicated with the leaking water extraction bottle through the water inlet on the sealing device; and the air inlet of a vacuum pumping device is communicated wit the leaking water extraction bottle through the air outlet on the sealing device. The underground leakage observation instrument is suitable for observation of underground leakage of paddy fields.