A seabed resource exploration system includes: a vibrator 1 for transmitting a sound wave into the sea and receiving a scattered wave in which the sound wave is reflected on a boundary surface between seawater and a mixture of methane gas and methane hydrate, which exists in the seawater; and an analyzer 17 for determining that the methane hydrate exists in a seabed immediately under the mixture when backscattering strength, calculated by the transmitted sound wave and the received scattered wave, is in a predetermined relationship. The predetermined relationship satisfies a relationship that a maximum value of the backscattering strength is -60 to -30 dB and an average value of the backscattering strength is -70 to -50 dB. The backscattering strength is on a grid obtained by cutting the mixture into round slices in the depth direction by a predetermined width, in a range from the seabed to a predetermined height.