ALARM

To provide an alarm that enhances usefulness in terms of ensuring a capacity at a time of employing a battery as a backup power source for a commercial power supply, and suppressing a cost.SOLUTION: An alarm includes: a primary power supply 21 that feeds electric power from a commercial power supply to a controller 35, a conducting/alarming display circuit 45, an audio alarming/failure detection circuit 47, an emergency lamp circuit 49, and an illuminance detection circuit 51; a battery holder 15 in which one of a dry battery 19 and a secondary battery 55 having the same shape as the dry battery is freely detachably and selectively fitted; an auxiliary power supply 39 that feeds electric power from the dry battery or the secondary battery, which is fitted in the battery holder, to the controller and the circuits 45, 47, 49, and 51 during power failure in the commercial power supply; and a charge circuit 43 that charges the secondary battery with electric power fed from the primary power supply while the secondary battery 55 fitted in the battery holder is not discharged.SELECTED DRAWING: Figure 3 【課題】商用電源のバックアップ電源に電池を用いる際の容量確保とコスト抑制の面での利便性を高める警報器を提供する。【解決手段】商用電源からの電力をコントローラ３５、通電／警報表示等回路４５、音声警報／故障検出回路４７、非常灯回路４９及び照度検出回路５１にに供給する主電源部２１と、乾電池１９及び同形状の二次電池５５のうちいずれか一方が着脱自在かつ選択的に装着される電池ホルダ１５と、商用電源の停電中に、電池ホルダに装着された乾電池又は二次電池の電力をコントローラ及び各回路４５、４７、４９、５１に供給する補助電源部３９と、電池ホルダに装着された二次電池５５の非放電中に、主電源部から供給される電力により二次電池を充電する充電回路４３とを備える。【選択図】図３