NOVELTY - The hydrogen generating device (100) comprises a casing (110) having a space and an opening, a button (120) integrally formed and connected to the casing to seal the opening, a solid reactant disposed in the casing, a bag-shaped body that is disposed in the casing and contains a liquid reactant, flexible elements connected to the casing and located in the containing space, and an absorbent enclosing the solid reactant or mixing with the solid reactant. The flexible elements include a bending end, and are located between the button and the bag-shaped body.    USE - The hydrogen generating device is useful for a fuel cell such as a proton exchange membrane fuel cell and a direct methanol fuel cell, which is useful in fields such as portable electronics, home power generating systems, transportation, military equipment, space industry and small power generating systems.    ADVANTAGE - The hydrogen generating device exhibits good airtight quality thus improving the hydrogen generation rate.    DETAILED DESCRIPTION - The hydrogen generating device (100) comprises a casing (110) having a space and an opening, a button (120) integrally formed and connected to the casing to seal the opening, a solid reactant disposed in the casing, a bag-shaped body that is disposed in the casing and contains a liquid reactant, flexible elements connected to the casing and located in the containing space, and an absorbent enclosing the solid reactant or mixing with the solid reactant. The flexible elements include a bending end, are located between the button and the bag-shaped body, are metallic pieces, and extend from two opposite inner walls of the casing. The button pushes the flexible element when it is pressed so the bending end pierces the bag-shaped body and the liquid reactant flows out and reacts with the solid reactant to generate hydrogen. The button is made of a thermoplastic elastomer. A material of the casing is a high polymer plastic. The button and the casing are fabricated through a double injection method. The bending end includes a sawtooth structure, a pin structure or a knife structure. The casing has an exhaust opening (112) linked to the containing space. The bending end extends in a direction towards the bag-shaped body.    DESCRIPTION OF DRAWING(S) - The diagram shows a schematic three-dimensional view of a hydrogen generating device.    Hydrogen generating device (100)    Casing (110)    Exhaust opening (112)    Button. (120)