To provide a liquid shut-off valve capable of suppressing machining precision to low extent comparatively and performing assembly work simply without requiring time and labor.

This liquid shut-off valve 20 is constituted in such a way that a body 21 is arranged in an upper part in a fuel tank 10, a partition wall 27 is attached to an upper part 21a in the body 21 to partition the inside of the body 21 into a main space 28 and an upper space 29, a first through hole 31 is formed at the center of the partition wall 27, a float 22 is arranged in the main space 28 below the first through hole 31 so as to rise and lower freely, a subvalve 32 is arranged between the float 22 and the first through hole 31, and a second through hole 33 having smaller diameter than that of the first through hole 31 is formed in the subvalve 32. In this liquid shut-off valve 20, the subvalve is attached to the float so as to move vertically, and the subvalve is put on a second valve element by self-weight, and a first valve element and the second valve element are formed by an elastically deformable member.