A selective hydrogen adding equipment is provided by which living organism applicable hydrogen-contained fluid is obtained without changing properties of the living organism applicable fluid. Living organism applicable hydrogen-contained fluid is obtained through storing a hydrogen generating system, which contains a hydrogen generating agent as an essential component, in a hydrogen bubble forming implement which has a gas/liquid separating section including a gas-permeable film or an open-close type valve, causing the hydrogen generating system and a generating-purpose water to react in the hydrogen bubble forming implement, and supplying hydrogen gas generated in the hydrogen bubble forming implement into living organism applicable fluid via the gas/liquid separating section.