A water level alarm device includes a first magnet, a second magnet, a wire, an insulated connection line, a floating body, an amplifier, and an alarm element. The wire passes through a gap between a north pole of the first magnet and a south pole of the second magnet. The floating body floats in water of a water storage equipment. When a water level of the water storage equipment is lower than a reference value, the floating body fastens the insulated connection line, the insulated connection line drives the wire to vibrate between the gap, and the wire cuts magnetic induction lines between the north pole of the first magnet and the south pole of the second magnet to generate induced current. The induced current is amplified by the amplifier and then is output to the alarm element, to control the alarm element to alarm.一種水位報警器,包括一第一磁鐵、一第二磁鐵、一導線、一絕緣連接線、一漂浮體、一放大器及一報警元件。該導線穿過該第一磁鐵的北極與該第二磁鐵的南極之間的縫隙。該漂浮體漂浮在一儲水設備的水中。當該儲水設備的水位低於一參考值時,該漂浮體繃緊該絕緣連接線,該絕緣連接線帶動該導線在該縫隙之間振動,該導線切割該第一磁鐵的北極與該第二磁鐵的南極之間的磁感線從而產生感應電流,該感應電流經該放大器放大後輸出給該報警元件,以控制該報警元件報警。100‧‧‧水位報警器110‧‧‧第一磁鐵120‧‧‧第二磁鐵130‧‧‧縫隙150‧‧‧導線160‧‧‧絕緣連接線170‧‧‧漂浮體180‧‧‧放大器190‧‧‧報警元件200‧‧‧儲水設備210‧‧‧水位220‧‧‧水
