Provided is an alkaline water electrolyzer in which leakage of aqueous alkali solutions is prevented.
The alkaline water electrolyzer 10 includes an anode chamber frame 11 defining an anode chamber 12; a cathode chamber frame 17 defining a cathode chamber 18; a porous diaphragm 16 disposed between the anode and cathode chamber frames 11 and 17 and partitioning the anode and cathode chambers 12 and 18; an anode gasket 15 disposed on the anode chamber frame 11; and a cathode gasket 21 disposed on the cathode chamber frame 17, wherein when the anode and cathode chamber frames 11 and 17 are fastened, the porous diaphragm 16 is held between the anode and cathode chamber frames 11 and 17 via the anode and cathode gaskets 15 and 21 and the anode and cathode gaskets 15 and 21 are in contact with each other around the peripheral edge of the porous diaphragm 16 by compressing the anode and cathode gaskets 15 and 21.