A leak hydrogen absorbing device is provided and includes an absorbing tank, having a gas inlet and a gas outlet; a spacer, disposed inside the absorbing tank, and partitioning an interior of the absorbing tank into multiple spaces; a hydrogen absorbing material, disposed in the spaces; a connecting tube, disposed on the spacer, and connecting the spaces; a pump, pumping a hydrogen-containing gas leaked in a closed environment to the absorbing tank through the gas inlet to be flowed through the spaces inside the absorbing tank, so that the hydrogen gas contained in the hydrogen-containing gas is absorbed by the hydrogen absorbing material; and a depressurizing portion, disposed at a terminal end of the absorbing tank, and storing a hydrogen-free gas passed through the hydrogen absorbing material. The hydrogen-free gas is discharged through the gas outlet when reaching a predetermined pressure.