The apparatus includes: a hydrogen generation container provided with a magnesium-based hydride accommodation part accommodating magnesium-based hydride; a reaction water tank storing water or an aqueous solution; the pipes connected to the reaction water tank and the hydrogen generation container; a pump operating to suction water or the aqueous solution from the reaction water tank and then exhaust it through the pipes to the hydrogen generation container; a pressure gauge measuring the pressure in the inside of the hydrogen generation container; and a control unit, on the basis of the pressure value of the pressure gauge, controlling the amount of water caused to flow through the pipes by the pump.